U.S. patent application number 12/156116 was filed with the patent office on 2009-02-05 for refrigeration apparatus with exhaust heat recovery device.
This patent application is currently assigned to DENSO CORPORATION. Invention is credited to Hironori Asa, Hiroshi Kishita, Michio Nishikawa, Keiichi Uno.
Application Number | 20090031749 12/156116 |
Document ID | / |
Family ID | 40030977 |
Filed Date | 2009-02-05 |
United States Patent
Application |
20090031749 |
Kind Code |
A1 |
Nishikawa; Michio ; et
al. |
February 5, 2009 |
Refrigeration apparatus with exhaust heat recovery device
Abstract
A refrigeration apparatus with an exhaust heat recovery device
mounted on a vehicle includes a refrigeration cycle for allowing a
refrigerant for refrigeration to circulate therethrough, and a
Rankine cycle for allowing a refrigerant for the Rankine cycle to
circulate therethrough. The refrigeration-cycle condenser and the
Rankine-cycle condenser are disposed in predetermined positions of
the vehicle in series with respect to a flow direction of external
air for cooling, and the refrigeration-cycle condenser is disposed
on an upstream side of the external air with respect to the
Rankine-cycle condenser.
Inventors: |
Nishikawa; Michio;
(Obu-city, JP) ; Asa; Hironori; (Okazaki-city,
JP) ; Uno; Keiichi; (Kariya-city, JP) ;
Kishita; Hiroshi; (Anjo-city, JP) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Assignee: |
DENSO CORPORATION
Kariya-city
JP
Nippon Soken, Inc.
Nishio-city
JP
|
Family ID: |
40030977 |
Appl. No.: |
12/156116 |
Filed: |
May 28, 2008 |
Current U.S.
Class: |
62/324.3 ;
62/501 |
Current CPC
Class: |
B60H 1/00921 20130101;
B60H 1/025 20130101; B60H 2001/00949 20130101 |
Class at
Publication: |
62/324.3 ;
62/501 |
International
Class: |
F25B 13/00 20060101
F25B013/00; F25B 1/00 20060101 F25B001/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 30, 2007 |
JP |
2007-144157 |
Claims
1. A refrigeration apparatus with an exhaust heat recovery device
mounted on a vehicle, comprising: a refrigeration cycle for
allowing a refrigerant for refrigeration to circulate therethrough,
the refrigeration cycle including a compressor, a
refrigeration-cycle condenser, an expansion valve, and an
evaporator which are connected in a circular shape; and a Rankine
cycle for allowing a refrigerant for the Rankine cycle to circulate
therethrough, the Rankine cycle including a pump, a heater using
exhaust heat from a heat engine of the vehicle as a heating source,
an expansion unit, and a Rankine-cycle condenser which are
connected in a circular shape, wherein the refrigeration-cycle
condenser and the Rankine-cycle condenser are disposed in
predetermined positions of the vehicle in series with respect to a
flow direction of external air for cooling, and wherein the
refrigeration-cycle condenser is disposed on an upstream side of
the external air with respect to the Rankine-cycle condenser.
2. The refrigeration apparatus with an exhaust heat recovery device
according to claim 1, further comprising control means for
controlling operations of the refrigeration cycle and the Rankine
cycle, wherein the control means controls number of revolutions of
the expansion unit such that an expansion-unit pressure difference
in the expansion unit of the refrigerant for the Rankine cycle is
equal to or more than a predetermined value, when both the
refrigeration cycle and the Rankine cycle are simultaneously
operated.
3. The refrigeration apparatus with an exhaust heat recovery device
according to claim 2, wherein the control means decreases the
number of revolutions of the expansion unit when the expansion-unit
pressure difference is smaller than the predetermined value.
4. The refrigeration apparatus with an exhaust heat recovery device
according to claim 2, wherein the control means controls the number
of revolutions of the expansion unit such that the expansion-unit
pressure difference has such a value as to obtain a predetermined
appropriate expansion ratio in the expansion unit.
5. The refrigeration apparatus with an exhaust heat recovery device
according to claim 2, further comprising: a high-pressure side
pressure detection means located in a high-pressure side area
leading from a downstream side of the pump to an upstream side of
the expansion unit, the high-pressure side pressure detection means
being adapted to detect a high-pressure side pressure of the
refrigerant for the Rankine cycle; and a low-pressure side pressure
detection means located in a low-pressure side area leading from a
downstream side of the expansion unit to an upstream side of the
pump, the low-pressure side pressure detection means being adapted
to detect a low-pressure side pressure of the refrigerant for the
Rankine cycle, wherein the control means controls the number of
revolutions of the expansion unit based on a difference between the
high-pressure side pressure and the low-pressure side pressure, the
difference indicating the expansion unit pressure difference.
6. The refrigeration apparatus with an exhaust heat recovery device
according to claim 2, further comprising: a high-pressure side
pressure detection means located in a high-pressure side area
leading from a downstream side of the pump to an upstream side of
the expansion unit, the high-pressure side pressure detection means
being adapted to detect a high-pressure side pressure of the
refrigerant for the Rankine cycle; an air temperature detection
means disposed between the refrigeration-cycle condenser and the
Rankine-cycle condenser, the air temperature detection means being
adapted to detect an air temperature of the external air passing
through between the refrigeration-cycle condenser and the
Rankine-cycle condenser; and calculation means for calculating a
temperature of the refrigerant for the Rankine cycle in the
Rankine-cycle condenser, and further a low-pressure side pressure
based on an amount of heat radiated at the Rankine-cycle condenser
which is balanced with an amount of heat absorbed into the heater
by exhaust heat, an amount of the external air passing through the
Rankine-cycle condenser, and the air temperature detected by the
air temperature detection means, wherein the control means controls
the number of revolutions of the expansion unit based on a
difference, indicative of the expansion-unit pressure difference,
between the high-pressure side pressure and the low-pressure side
pressure.
7. The refrigeration apparatus with an exhaust heat recovery device
according to claim 2, further comprising: a high-pressure side
pressure detection means located in a high-pressure side area
leading from a downstream side of the pump to an upstream side of
the expansion unit, the high-pressure side pressure detection means
being adapted to detect a high-pressure side pressure of the
refrigerant for the Rankine cycle; an inflow air temperature
detection means for detecting an inflow air temperature of the
external air before flowing into the refrigeration-cycle condenser
and the Rankine-cycle condenser; and calculation means for
calculating a temperature of the external air after passing through
the refrigeration-cycle condenser based on an amount of heat
radiated at the refrigeration radiator which is balanced with a
necessary refrigeration capacity at the evaporator, an amount of
the external air passing through the refrigeration-cycle condenser,
and the inflow air temperature detected by the inflow air
temperature detection means, the calculation means being also
adapted to calculate a temperature of the refrigerant for the
Rankine cycle in the Rankine-cycle condenser, and further
calculating a low-pressure side pressure based on an amount of heat
radiated at the Rankine-cycle condenser which is balanced with an
amount of heat absorbed into the heater by the exhaust heat, an
amount of the external air passing through the Rankine-cycle
condenser, and the calculated temperature of the external air after
passing through the refrigeration-cycle condenser, wherein the
control means controls the number of revolutions of the expansion
unit based on a difference, indicative of the expansion-unit
pressure difference, between the high-pressure side pressure and
the low-pressure side pressure.
8. The refrigeration apparatus with an exhaust heat recovery device
according to claim 1, wherein positions of an inlet and an outlet
of the refrigerant in the refrigeration-cycle condenser are
positioned in the same area as those of an inlet and an outlet of
the refrigerant for the Rankine cycle in the Rankine-cycle
condenser as viewed from the flow direction of the external
air.
9. The refrigeration apparatus with an exhaust heat recovery device
according to claim 1, further comprising an air-introduction flow
path portion for allowing the external air to be introduced into
the Rankine-cycle condenser from an upstream side of the external
air of the refrigeration-cycle condenser through a space between
the refrigeration-cycle condenser and the Rankine-cycle condenser,
and an opening adjustment portion for adjusting an area of an
opening toward the refrigeration-cycle condenser and an area of an
opening toward the air-introduction flow path portion by being
moved under control of the control means.
10. The refrigeration apparatus with an exhaust heat recovery
device according to claim 1, wherein an area of a front surface of
the refrigeration-cycle condenser is made to be smaller than that
of a front surface of the Rankine-cycle condenser, and the
Rankine-cycle condenser has an area at an upstream side of the
external air where the refrigeration-cycle condenser is not
superimposed.
11. The refrigeration apparatus with an exhaust heat recovery
device according to claim 10, wherein a dimension of the
refrigeration-cycle condenser in a flow direction of the external
air is set larger than that of the Rankine-cycle condenser.
12. The refrigeration apparatus with an exhaust heat recovery
device according to claim 1, wherein an inlet and an outlet of the
refrigerant for refrigeration in the refrigeration-cycle condenser
is provided to be opened toward an upstream side in a flow
direction of the external air.
13. The refrigeration apparatus with an exhaust heat recovery
device according to claim 1, wherein an inlet and an outlet of the
refrigerant for the Rankine cycle in the Rankine-cycle condenser is
provided to be opened in a direction perpendicular to a flow
direction of the external air.
14. The refrigeration apparatus with an exhaust heat recovery
device according to claim 1, wherein the refrigeration-cycle
condenser and the Rankine-cycle condenser are disposed on an
upstream side of the external air with respect to a radiator
located in a radiator circuit of the vehicle, and wherein the
refrigeration-cycle condenser, the Rankine-cycle condenser, and the
radiator are disposed at predetermined positions of the vehicle in
series with respect to a flow direction of the external air for
cooling.
15. The refrigeration apparatus with an exhaust heat recovery
device according to claim 14, wherein the refrigeration-cycle
condenser, the Rankine-cycle condenser, and the radiator are
disposed on a front side in an engine room, at a rear side of a
vehicle grill.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based on Japanese Patent Application No.
2007-144157 filed on May 30, 2007, the contents of which are
incorporated herein by reference in its entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to a refrigeration apparatus
with an exhaust heat recovery device for operating an expansion
unit using exhaust heat from a vehicle, for example, an internal
combustion engine, as a heating source.
BACKGROUND OF THE INVENTION
[0003] A conventional refrigeration apparatus with an exhaust heat
recovery device is known in, for example, JP-A-2006-46763. The
refrigeration apparatus includes a refrigeration cycle and a
Rankine cycle using exhaust heat in cooling of an internal
combustion engine serving as a heat generator. A compressor for
compressing and discharging refrigerant in the refrigeration cycle
and an expansion unit adapted to be operated in the Rankine cycle
by expansion of refrigerant heated by the exhaust heat in cooling
of the internal combustion engine are respectively independently
located. A condenser (radiator) in the Rankine cycle is also used
and configured as a condenser for the refrigeration cycle.
[0004] Such a refrigeration apparatus permits independent operation
of the refrigeration cycle or the Rankine cycle, or the
simultaneous operation of both the refrigeration cycle and the
Rankine cycle according to the necessity of cooling operation for a
vehicle compartment and the possibility of recovery of the exhaust
heat in cooling.
[0005] In the above-mentioned refrigeration apparatus, however,
when the refrigeration cycle and the Rankine cycle are
simultaneously driven, the condenser condenses the refrigerant in
both the cycles (i.e., radiates heat from both the cycles) at the
same time, resulting in an increase in pressure of the refrigerant
at the condenser. This leads to an increase in power of the
compressor in the refrigeration cycle, thus resulting in reduction
of reliability on the compressor, and also a decrease in
coefficient of performance of the refrigeration cycle.
[0006] Further, the single operation of only the Rankine cycle may
cause a difference in pressure between the condenser and the
evaporator in accordance with an increase in pressure of the
refrigerant at the condenser even though the refrigeration cycle is
stopped, thereby allowing the refrigerant to be collected in the
refrigeration cycle side (evaporator side). This may result in a
decrease in amount of the refrigerant on the Rankine cycle side, so
that an inherent capability of the Rankine cycle cannot be
sufficiently exhibited. Moreover, because lubricating oil contained
in the refrigerant may also be collected in the refrigeration
cycle, shortage of lubrication of the expansion unit or a
refrigerant pump may be caused, thus resulting in reduction of
reliability on the expansion unit and refrigerant pump.
SUMMARY OF THE INVENTION
[0007] The invention has been made in view of the foregoing
problems, and it is an object of the invention to provide a
refrigeration apparatus with an exhaust heat recovery device, which
includes a refrigeration cycle and a Rankine cycle and which can
exhibit sufficient performance to both the cycles while ensuring
reliability thereon.
[0008] According to an aspect of the present invention, a
refrigeration apparatus with an exhaust heat recovery device
mounted on a vehicle includes: a refrigeration cycle for allowing a
refrigerant for refrigeration to circulate therethrough; and a
Rankine cycle for allowing a refrigerant for the Rankine cycle to
circulate therethrough. The refrigeration cycle includes a
compressor, a refrigeration-cycle condenser, an expansion valve,
and an evaporator which are connected in a circular shape. The
Rankine cycle includes a pump, a heater using exhaust heat from a
heat engine of the vehicle as a heating source, an expansion unit,
and a Rankine-cycle condenser which are connected in a circular
shape. In the refrigeration apparatus, the refrigeration-cycle
condenser and the Rankine-cycle condenser are disposed in
predetermined positions of the vehicle in series with respect to a
flow direction of external air for cooling, and the
refrigeration-cycle condenser is disposed on an upstream side of
the external air with respect to the Rankine-cycle condenser.
[0009] Accordingly, regardless of the presence or absence of the
operation of the Rankine cycle, the refrigeration-cycle condenser
constantly allows an external fluid whose temperature is equal to
the temperature of outside air to flow thereinto. In operation of
the refrigeration cycle, it does not lead to reduction in
reliability on the refrigeration cycle together with deterioration
of power of the compressor, as well as a decrease in refrigeration
capacity due to a decrease in coefficient of performance.
[0010] Further, in single operation of the Rankine cycle, each
cycle constructs a corresponding independent refrigerant circuit,
and thus the refrigerant and lubricating oil are not collected from
the Rankine cycle into the refrigeration cycle. Accordingly, it can
sufficiently exhibit the inherent capacity of the Rankine cycle,
and ensure the reliability on the expansion unit and the pump.
Thus, the refrigeration apparatus with the exhaust heat recovery
device can exhibit sufficient performance to both the cycles, while
ensuring the reliability thereon.
[0011] For example, the refrigeration apparatus may be provided
with a control means for controlling operations of the
refrigeration cycle and the Rankine cycle. In this case, the
control means controls number of revolutions of the expansion unit
such that an expansion-unit pressure difference in the expansion
unit of the refrigerant for the Rankine cycle is equal to or more
than a predetermined value, when both the refrigeration cycle and
the Rankine cycle are simultaneously operated. Accordingly, even in
the simultaneously operating of the refrigeration cycle and the
Rankine cycle, it is possible to ensure a sufficient pressure
difference of the expansion unit so as to obtain a sufficient
regenerative power by the expansion unit, while preventing an
unstable operation of the Rankine cycle.
[0012] Furthermore, the control means decreases the number of
revolutions of the expansion unit when the expansion-unit pressure
difference is smaller than the predetermined value. Accordingly, it
is possible to accurately set the expansion-unit pressure
difference to be equal to or larger than the predetermined
value.
[0013] The control means controls the number of revolutions of the
expansion unit such that the expansion-unit pressure difference has
such a value as to obtain a predetermined appropriate expansion
ratio in the expansion unit. This can appropriately expand and
operate the expansion unit, thereby effectively regenerating the
power by the expansion unit.
[0014] The refrigeration apparatus may be further provided with a
high-pressure side pressure detection means located in a
high-pressure side area leading from a downstream side of the pump
to an upstream side of the expansion unit, and a low-pressure side
pressure detection means located in a low-pressure side area
leading from a downstream side of the expansion unit to an upstream
side of the pump. The high-pressure side pressure detection means
is adapted to detect a high-pressure side pressure of the
refrigerant for the Rankine cycle, and the low-pressure side
pressure detection means is adapted to detect a low-pressure side
pressure of the refrigerant for the Rankine cycle. In this case,
the control means may control the number of revolutions of the
expansion unit based on a difference between the high-pressure side
pressure and the low-pressure side pressure. Here, the difference
indicates the expansion-unit pressure difference.
[0015] Alternatively, the refrigeration apparatus may be provided
with a high-pressure side pressure detection means located in a
high-pressure side area leading from a downstream side of the pump
to an upstream side of the expansion unit, an air temperature
detection means disposed between the refrigeration-cycle condenser
and the Rankine-cycle condenser, and a calculation means. The
high-pressure side pressure detection means is adapted to detect a
high-pressure side pressure of the refrigerant for the Rankine
cycle, and the air temperature detection means is adapted to detect
an air temperature of the external air passing through between the
refrigeration-cycle condenser and the Rankine-cycle condenser. The
control means is adapted to calculate a temperature of the
refrigerant for the Rankine cycle in the Rankine-cycle condenser,
and further a low-pressure side pressure based on an amount of heat
radiated at the Rankine-cycle condenser which is balanced with an
amount of heat absorbed into the heater by exhaust heat, an amount
of the external air passing through the Rankine-cycle condenser,
and the air temperature detected by the air temperature detection
means. In this case, the control means may control the number of
revolutions of the expansion unit based on a difference, indicative
of the expansion-unit pressure difference, between the
high-pressure side pressure and the low-pressure side pressure.
[0016] Accordingly, it is possible to calculate (estimate) the
expansion-unit pressure difference using the low-pressure side
pressure detection means instead of the air temperature detection
means, and also using the calculation means.
[0017] Alternatively, the refrigeration apparatus may be provided
with: a high-pressure side pressure detection means located in a
high-pressure side area leading from a downstream side of the pump
to an upstream side of the expansion unit, to detect a
high-pressure side pressure of the refrigerant for the Rankine
cycle; an inflow air temperature detection means for detecting an
inflow air temperature of the external air before flowing into the
refrigeration-cycle condenser and the Rankine-cycle condenser; and
calculation means for calculating a temperature of the external air
after passing through the refrigeration-cycle condenser based on an
amount of heat radiated at the refrigeration radiator which is
balanced with a necessary refrigeration capacity at the evaporator,
an amount of the external air passing through the
refrigeration-cycle condenser, and the inflow air temperature
detected by the inflow air temperature detection means. The
calculation means is also adapted to calculate a temperature of the
refrigerant for the Rankine cycle in the Rankine-cycle condenser,
and further calculating a low-pressure side pressure based on an
amount of heat radiated at the Rankine-cycle condenser which is
balanced with an amount of heat absorbed into the heater by the
exhaust heat, an amount of the external air passing through the
Rankine-cycle condenser, and the calculated temperature of the
external air after passing through the refrigeration-cycle
condenser. In this case, the control means may control the number
of revolutions of the expansion unit based on a difference,
indicative of the expansion-unit pressure difference, between the
high-pressure side pressure and the low-pressure side pressure.
[0018] In the refrigeration apparatus, positions of an inlet and an
outlet of the refrigerant in the refrigeration-cycle condenser may
be set in the same area as those of an inlet and an outlet of the
refrigerant for the Rankine cycle in the Rankine-cycle condenser as
viewed from the flow direction of the external air.
[0019] Thus, an inflow area and an outflow area of the refrigerant
for refrigeration in the refrigeration-cycle condenser can have the
same positional relationship as that of an inflow area and an
outflow area of the refrigerant for the Rankine cycle in the
Rankine-cycle condenser. The amount of increase in temperature of
the external air having passed through the refrigeration-cycle
condenser is high on the inflow side of the refrigerant for
refrigeration, and becomes lower toward the outflow side. It is
apparent that the temperature of the refrigerant for the Rankine
cycle in the Rankine-cycle condenser becomes lower from the inflow
side toward the outflow side by heat exchange. This can provide
such a positional relationship that temperature distribution of the
external air flowing into the Rankine-cycle condenser has the same
tendency as that of the refrigerant for the Rankine cycle into the
Rankine-cycle condenser. Thus, a difference in temperature between
the external air and the refrigerant for the Rankine cycle can be
entirely made uniform, which can effectively radiate heat from the
Rankine-cycle condenser.
[0020] Alternatively, the refrigeration apparatus may be further
provided with: an air-introduction flow path portion for allowing
the external air to be introduced into the Rankine-cycle condenser
from an upstream side of the external air of the
refrigeration-cycle condenser through a space between the
refrigeration-cycle condenser and the Rankine-cycle condenser; and
an opening adjustment portion for adjusting an area of an opening
toward the refrigeration-cycle condenser and an area of an opening
toward the air-introduction flow path portion by being moved under
control of the control means.
[0021] Thus, the amount of external air flowing into each condenser
can be adjusted according to the necessary amount of heat radiated
from each of the condensers for the refrigeration cycle and the
Rankine cycle, so as to enable effective heat radiation at the
respective condensers.
[0022] Furthermore, an area of a front surface of the
refrigeration-cycle condenser may be made to be smaller than that
of a front surface of the Rankine-cycle condenser, and the
Rankine-cycle condenser may have an area at an upstream side of the
external air where the refrigeration-cycle condenser is not
superimposed. Thus, the external air whose temperature is equal to
the outside air temperature and which is not subjected to the heat
exchange at the refrigeration-cycle condenser can flow directly
into the Rankine-cycle condenser, so that the radiation capacity of
the radiator for the Rankine cycle can be improved.
[0023] Alternatively, a dimension of the refrigeration-cycle
condenser in a flow direction of the external air may be set larger
than that of the Rankine-cycle condenser. Accordingly, it is
possible to obtain a higher heat radiation capacity of the
refrigeration-cycle condenser by increasing a dimension of the
external air in the direction of flow, and easily decrease an area
of the front surface of the refrigeration-cycle condenser.
[0024] Alternatively, the inlet and the outlet of the refrigerant
for refrigeration in the refrigeration-cycle condenser may be
provided to be opened toward an upstream side in a flow direction
of the external air. Thus, it is not necessary to dispose piping
between the refrigeration-cycle condenser and the Rankine-cycle
condenser in routing piping for refrigerant in the
refrigeration-cycle condenser. This does not degrade the
dimensional accuracy between both the condensers, and enables easy
connection of the piping to the refrigeration-cycle condenser.
[0025] Furthermore, the inlet and the outlet of the refrigerant for
the Rankine cycle in the Rankine-cycle condenser may be provided to
be opened in a direction perpendicular to a flow direction of the
external air.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Additional objects and advantages of the present invention
will be more readily apparent from the following detailed
description of preferred embodiments when taken together with the
accompanying drawings. In which:
[0027] FIG. 1 is a schematic diagram showing an entire system of a
refrigeration apparatus with an exhaust heat recovery device
according to a first embodiment of the invention;
[0028] FIG. 2 is a side view showing a mounting state of a
refrigeration-cycle condenser, a Rankine-cycle condenser, and a
radiator on a vehicle in the first embodiment;
[0029] FIG. 3 is a perspective view showing an inlet and an outlet
for refrigerant of each of the refrigeration-cycle condenser and
the Rankine-cycle condenser in the first embodiment;
[0030] FIG. 4 is a perspective view showing connection directions
of piping with the inlets and outlets for refrigerant and for
coolant in each of the refrigeration-cycle condenser, the
Rankine-cycle condenser, and the radiator in the first
embodiment;
[0031] FIG. 5 is a control characteristic diagram showing an
operation mode of an electric fan with respect to a refrigerant
pressure in the first embodiment;
[0032] FIG. 6 is a flowchart showing a control method for
simultaneously operating the refrigeration cycle and the Rankine
cycle in the first embodiment;
[0033] FIG. 7 is a schematic diagram showing an entire system of a
refrigeration apparatus with an exhaust heat recovery device
according to a second embodiment of the invention;
[0034] FIG. 8 is a flowchart showing a control method for
simultaneously operating the refrigeration cycle and the Rankine
cycle in the second embodiment;
[0035] FIG. 9 is a schematic diagram showing an entire system of a
refrigeration apparatus with an exhaust heat recovery device
according to a third embodiment of the invention;
[0036] FIG. 10 is a flowchart showing a control method for
simultaneously operating the refrigeration cycle and the Rankine
cycle in the third embodiment;
[0037] FIG. 11 is a plan view showing a duct and a guide in a
fourth embodiment of the invention;
[0038] FIG. 12 is a perspective view showing a refrigeration-cycle
condenser and a Rankine-cycle condenser in a fifth embodiment of
the invention; and
[0039] FIG. 13 is a perspective view for supplemental explanation
showing the refrigeration-cycle condenser and the Rankine-cycle
condenser in the fifth embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
First Embodiment
[0040] A first embodiment of the invention is shown in FIGS. 1 to
6. First, the specific structure of the first embodiment will be
described below. FIG. 1 is a schematic diagram showing an entire
system of a refrigeration apparatus 100A with an exhaust heat
recovery device (hereinafter referred to as a "refrigeration
apparatus"). FIG. 2 is a side view showing a mounting state of a
refrigeration-cycle condenser 220 (hereinafter referred to as an
"AC condenser"), a Rankine-cycle condenser 340 (hereinafter
referred to as an "RA condenser"), and a radiator 21 on a vehicle.
FIG. 3 is a perspective view showing inlets 220a and 340a and
outlets 220b and 340b for refrigerant of the AC condenser 220 and
the RA condenser 340. FIG. 4 is a perspective view showing
connection directions of piping with the inlets 220a, 340a, and
21a, and the outlets 220b, 340b, and 21b for refrigerant and
coolant of the AC condenser 220, the RA condenser 340, and the
radiator 21. FIG. 5 is a control characteristic diagram showing
operation modes of an electric fan 260 with respect to refrigerant
pressures. FIG. 6 is a flowchart 1 showing a control method for
simultaneously operating a refrigeration cycle 200 and a Rankine
cycle 300.
[0041] As shown in FIG. 1, the refrigeration apparatus 100A of the
first embodiment is applied to a vehicle using an engine 10 as a
driving source. The refrigeration apparatus 100A is provided with
the refrigeration cycle 200 and the Rankine cycle 300. The
operations of the respective cycles 200 and 300 are controlled by
an energization control circuit 50.
[0042] The engine 10 is a water-cooled internal combustion engine
(corresponding to a heat engine in the invention), and is provided
with a radiator circuit 20 for cooling the engine 10 by circulation
of engine coolant, and a heater circuit 30 for heating conditioned
air (i.e., air to be conditioned) using the coolant (warm water) as
a heating source.
[0043] The radiator circuit 20 is provided with the radiator 21,
which cools the coolant circulating by a warm water pump 22, by
performing heat exchange with outside air. The warm pump 22 may be
either an electric pump or a mechanical pump. A heater 320 in the
Rankine cycle 300 to be described later is disposed in a flow path
on the outlet side of the engine (in a flow path between the engine
10 and the radiator 21), so that the coolant flows through the
heater 320. A radiator bypass flow path 23 for bypassing the
radiator 21 and for allowing the coolant to flow therethrough is
provided in the radiator circuit 20. A thermostat 24 adjusts an
amount of coolant flowing through the radiator 21 and an amount of
coolant flowing through the radiator bypass flow path 23.
[0044] The heater circuit 30 is provided with a heater core 31, and
allows the coolant (warm water) to circulate therethrough by the
above-mentioned warm water pump 22. The heater core 31 is disposed
in an air conditioning case 410 of an air conditioning unit 400,
and heats the conditioned air blown by the blower 420 by heat
exchange with the warm water. The heater core 31 is provided with
an air mix door 430. The air mix door 430 is opened or closed to
adjust the amount of conditioned air flowing through the heater
core 31.
[0045] The refrigeration cycle 200 includes a compressor 210, an AC
condenser 220, a liquid receiver 230, an expansion valve 240, and
an evaporator 250, which are connected in an annular shape to form
a closed circuit. The compressor 210 is a fluid device for
compressing refrigerant in the refrigeration cycle 200 at a high
temperature and a high pressure (here, the refrigerant corresponds
to refrigerant for refrigeration in the invention, and which is
hereinafter referred to as an "AC refrigerant"). The compressor 210
is driven by a driving force of the engine 10. That is, a pulley
211 serving as driving means is fixed to a driving shaft of the
compressor 210, so that the driving force of the engine 10 is
transferred to the pulley 211 via a belt 11 to drive the compressor
210. The pulley 211 is provided with an electromagnetic clutch not
shown for intermittently connecting between the compressor 210 and
the pulley 211. The intermittent connection of the electromagnetic
clutch is controlled by the energization control circuit 50 to be
described later. The AC refrigerant circulates through the
refrigeration cycle 200 by operating the compressor 210.
[0046] The AC condenser 220 is connected to the discharge side of
the compressor 210. The condenser 220 is a heat exchanger for
condensing and liquifying the AC refrigerant flowing therethrough
by heat exchange with cooling air (corresponding to external air in
the invention). The liquid receiver 230 is a receiver for
separating the AC refrigerant condensed by the AC condenser 220
into two liquid-gas phases, and allows the only liquefied AC
refrigerant separated to flow out toward the expansion valve 240.
The expansion valve 240 decompresses and expands the liquefied AC
refrigerant from the liquid receiver 230. This embodiment employs a
thermal expansion valve for isentropically decompressing the AC
refrigerant, and for controlling an opening degree of a throttle
such that a degree of superheat of the AC refrigerant drawn from
the evaporator 250 into the compressor 210 has a predetermined
value.
[0047] The evaporator 250 is disposed in the air conditioning case
410 of the air conditioning unit 400, like the heater core 31. The
evaporator 250 is a heat exchanger for evaporating the AC
refrigerant decompressed and expanded by the expansion valve 240,
and for cooling the conditioned air from the blower 420 by latent
heat of the evaporation at that time. The refrigerant outlet side
of the evaporator 250 is connected to the suction side of the
compressor 210. A mixture ratio of air cooled by the evaporator 250
to air heated by the heater core 31 is changed according to the
opening degree of the air mix door 430, so that the temperature of
the conditioned air is adjusted to a certain temperature set by a
passenger.
[0048] In contrast, the Rankine cycle 300 is adapted to recover
exhaust heat energy generated by the engine 10 (heat from the
coolant), and to convert the exhaust heat energy into mechanical
energy (a driving force of the expansion unit 330), and further
into electric energy (electric power generated by an electric
generator 331) in use. The Rankine cycle 300 will be described
below.
[0049] The Rankine cycle 300 includes a pump 310, a heater 320, an
expansion unit 330, a condenser 340, and a liquid receiver 350,
which are connected in an annular shape to form a closed
circuit.
[0050] The pump 310 is an electric pump for allowing the
refrigerant in the Rankine cycle 300 to circulate therethrough
(which corresponds to refrigerant for the Rankine cycle in the
invention, and which is hereinafter referred to as an "RA
refrigerant") using an electric motor 311 as a driving source. The
electric motor 311 is operated by the energization control circuit
50 to be described later. The RA refrigerant is the same
refrigerant as the above-mentioned AC refrigerant. The heater 320
is a heat exchanger for heating the RA refrigerant by heat exchange
between the RA refrigerant fed from the pump 310 and the
high-temperature coolant circulating through the radiator circuit
20.
[0051] The expansion unit 330 is a fluid device for generating a
rotation driving force by expansion of the superheated-steam RA
refrigerant heated by the heater 320. The electric generator 331 is
connected to a driving shaft of the expansion unit 330. The
electric generator 331 is operated by the driving force of the
expansion unit 330 as will be described later, so that electric
power generated by the electric generator 331 is charged into a
battery 40 via an inverter 51 included in the energization control
circuit 50 to be described later. The RA refrigerant flowing from
the expansion unit 330 leads to the RA condenser 340.
[0052] The RA condenser 340 is connected to the discharge side of
the expansion unit 330. The condenser 340 is a heat exchanger for
condensing and liquifying the RA refrigerant flowing therethrough
by heat exchange with cooling air (corresponding to external air in
the invention). The liquid receiver 350 is a receiver for
separating the RA refrigerant condensed by the RA condenser 340
into two liquid-gas phases, and allows only the separated liquid RA
refrigerant to flow out toward the pump 310.
[0053] A pressure sensor (corresponding to high-pressure side
pressure detection means in the invention) 301 for detecting a
pressure of the RA refrigerant (a high-pressure side pressure PHr)
is provided at a high-pressure side area leading from the discharge
side (downstream side) of the pump 310 of the Rankine cycle 300 to
the inflow side (upstream side) of the expansion unit 330. The
pressure sensor 301 is disposed between the heater 320 and the
expansion unit 330 in the high-pressure side area. Another pressure
sensor (corresponding to low-pressure side pressure detection means
in the invention) 302 for detecting a pressure of the RA
refrigerant (a low-pressure side pressure PLr) is provided at a
low-pressure side area leading from the discharge side (downstream
side) of the expansion unit 330 to the suction side (upstream side)
of the pump 310. The pressure sensor 302 is disposed between the
expansion unit 330 and the RA condenser 340 in the low-pressure
side area. Pressure signals detected by both the pressure sensors
301 and 302 are output to the energization control circuit 50 to be
described later.
[0054] As shown in FIG. 2, the AC condenser 220 in the
refrigeration cycle 200, the RA condenser 340 in the Rankine cycle
300, and the radiator 21 in the radiator circuit 20 are arranged on
the rear side of a vehicle grill, that is, on the front side of an
engine room. In running of the vehicle, the cooling air (external
air) flows from the vehicle grill into the engine room. The AC
condenser 220, the RA condenser 340, and the radiator 21 are
arranged in series in that order from the upstream side to the
downstream side with respect to the flow direction of the cooling
air and mounted on the vehicle. The upstream side of the flow
direction of the cooling air will be referred to as a "front side"
and the downstream side as a "rear side" with respect to a position
in the front/back direction of the vehicle.
[0055] As shown in FIG. 3, the inlet 220a and the outlet 220b for
the AC refrigerant are provided on one end side in the horizontal
direction of the AC condenser 220 (on the right side in mounting of
the condenser on the vehicle). The inlet 220a is disposed on the
upper side (on the upper right side in mounting), and the outlet
220b on the lower side (on the lower right side in mounting). The
inlet 340a and the outlet 340b of the RA refrigerant with respect
to the RA condenser 340 are positioned in the same respective areas
as those of the inlet 220a and the outlet 220b with respect to the
AC condenser 220. That is, the positions of the inlet 220a of the
AC condenser 220 and of the inlet 340a of the RA condenser 340 are
positioned on the upper right side in mounting of the condensers on
the vehicle. The positions of the outlet 220b of the AC condenser
220 and of the outlet 340b of the RA condenser 340 are positioned
on the lower right side in mounting.
[0056] Further, as shown in FIG. 4, the inlet 220a and the outlet
220b of the AC condenser 220 are opened to the forward side (the
grill side), and the refrigerant piping is connected from the front
side to the rear side. The inlet 340a and the outlet 340b of the RA
condenser 340 are opened in the direction perpendicular to the flow
direction of the cooling air (to the right side in the width
direction of the vehicle), and the refrigerant piping is connected
from the right side to the left side in the width direction. The
inlet 21a and the outlet 21b of the coolant of the radiator 21 are
opened toward the rear side (toward the engine 10 side), and the
coolant piping is connected from the rear side to the front
side.
[0057] An electric fan 260 in which an axial blower fan is
rotatably driven by an electric motor serving as a driving source
is provided on the rear side of the radiator 21 among the AC
condenser 220, the RA condenser 340, and the radiator 21 arranged
in series in the engine room (see FIG. 1). The electric fan 260 is
the so-called suction-type blowing means for forcedly supplying the
cooling air to the AC condenser 220, the RA condenser 340, and the
radiator 21 from the front side to the rear side by rotatably
driving the fan. When the sufficient amount of inflow of the
cooling air is not expected from the vehicle grill (in idling, in
climbing a slope at low speeds, or the like), and also when
radiation capacities of the AC condenser 220, the RA condenser 340,
and the radiator 21 cannot be derived sufficiently, the electric
fan 260 is operated to promote the supply of the cooling air.
[0058] Specifically, as shown in FIG. 5, the operation of the
electric fan 260 is controlled by the energization control circuit
50 to be described later. When a high-pressure side AC refrigerant
pressure of the refrigeration cycle 200 is equal to or less than
.alpha. (or when a temperature of coolant is equal to or less than
a predetermined temperature), the electric fan 260 is operated in a
Low mode (Lo mode). Further, when a high-pressure side AC
refrigerant pressure is equal to or more than .alpha.+.beta. (or
when a temperature of coolant is equal to or more than a
predetermined temperature+.gamma.), the electric fan 260 is
operated in a High mode (Hi mode).
[0059] The energization control circuit 50 is control means for
controlling the operations of various devices in the
above-mentioned refrigeration cycle 200 and the Rankine cycle 300,
and includes the inverter 51 and a controller 52.
[0060] The inverter 51 is to control the operation of the electric
generator 331 connected to the expansion unit 330. When the
electric generator 331 is operated by the driving force of the
expansion valve 330, the inverter 51 charges the generated power
into the battery 40.
[0061] The controller 52 controls the operation of the inverter 51.
Also, the controller 52 controls the electromagnetic clutch, the
electric fan 260, the electric motor 311 of the pump 310, and the
like by obtaining detection signals from the pressure sensors 301
and 302 in operating the refrigeration cycle 200 and the Rankine
cycle 300.
[0062] Now, the operations and effects of this arrangement will be
described below.
[0063] 1. Single Operation of Refrigeration Cycle
[0064] When a request for air conditioning is made while no exhaust
heat is obtained during warming or the like directly after the
startup of the engine 10, the energization control circuit 50 stops
the electric motor 311 of the pump 310 (while stopping the
expansion unit 320), engages the electromagnetic clutch, drives the
compressor 210 by the driving force of the engine 10, and singly
drives the refrigeration cycle 200. In this case, the refrigeration
cycle 200 operates in the same way as a normal air conditioner for
a vehicle.
[0065] 2. Single Operation of Rankine Cycle
[0066] When the sufficient exhaust heat is generated from the
engine 10 without an requirement for air conditioning, the
energization control circuit 50 disconnects the electromagnetic
clutch (stops the compressor 210), operates the electric motor 311
(the pump 310), and singly operates the Rankine cycle 300 thereby
to generate electricity.
[0067] In this case, the RA liquid refrigerant in the liquid
receiver 350 has a pressure increased by the pump 310 to be fed to
the heater 320. By the heater 320, the RA liquid refrigerant is
heated by high-temperature engine coolant to become RA superheated
steam refrigerant, which is fed to the expansion unit 330. The RA
superheated steam refrigerant is isentropically expanded and
decompressed by the expansion unit 330, and has part of thermal
energy and pressure energy converted into a rotation driving force.
The rotation driving force taken by the expansion unit 330 operates
the electric generator 331, which then generates the electricity.
The electric power generated by the electric generator 331 is
charged into the buttery 40 via the inverter 51, and then used for
operations of various auxiliary devices. The RA refrigerant
decompressed by the expansion unit 330 is condensed by the RA
condenser 340, separated into liquid and gas phases by the liquid
receiver 350, and drawn again into the pump 310.
[0068] 3. Simultaneous Operation of Refrigeration Cycle and Rankine
Cycle
[0069] When exhaust heat is sufficiently generated with a
requirement for air conditioning made, the energization control
circuit 50 simultaneously drives and operates both the
refrigeration cycle 200 and the Rankine cycle 300, thereby
performing both of the air conditioning and the electricity
generation.
[0070] In this case, the electromagnetic clutch is connected or
engaged to operate the electric motor 311 (pump 310). The AC
refrigerant and the RA refrigerant respectively circulate through
the refrigeration cycle 200 and the Rankine cycle 300. The
operation of each of the cycles 200 and 300 is the same as that in
singly operating thereof.
[0071] Since the RA condenser 340 is disposed on the rear side of
the AC condenser 220 in simultaneous operation of the
above-mentioned refrigeration cycle and Rankine cycle, the cooling
air having the outside air temperature flows into the AC condenser
220, and the cooling air whose temperature is increased by heat
exchange at the AC condenser 220 flows into the RA condenser 340.
Thus, the RA condenser 340 has a lower radiation capacity as
compared to a case where the cooling air having the outside air
temperature (external air not being affected by the heat exchange)
purely flows into the RA condenser 340. Together with this, a
low-pressure side pressure PLr of the Rankine cycle 300 is
increased. The increase in low-pressure side pressure PLr decreases
a pressure difference .DELTA.P of the expansion unit of the RA
refrigerant at the expansion unit 330, so that the driving force
regenerated is reduced, resulting in a decrease in amount of
electricity generated. Further, the operation of the Rankine cycle
300 becomes unstable. Thus, in order to suppress the decrease in
amount of electricity generated and prevent the unstable operation
of the Rankine cycle 300, the energization control circuit 50
performs control for preventing a decrease in pressure difference
based on a control flowchart 1 shown in FIG. 6.
[0072] That is, when the refrigeration cycle and the Rankine cycle
are simultaneously driven in step S100, first, the energization
control circuit 50 reads in a high-pressure side pressure PHr and a
low-pressure side pressure PLr detected by the pressure sensors 301
and 302 in step S110. In step S120, the low-pressure side pressure
PLr is subtracted from the high-pressure side pressure PHr thereby
to calculate a pressure difference .DELTA.P of the expansion
unit.
[0073] Then, in step S130, it is determined whether or not the
expansion unit pressure difference .DELTA.P calculated in the
above-mentioned step S120 is smaller than a predetermined pressure
difference .DELTA.Pa (corresponding to a predetermined value in the
invention). The predetermined pressure difference .DELTA.Pa is
defined as a lower limit of the pressure difference which allows
overexpansion of the expansion unit 330, while enabling the stable
operation of the Rankine cycle 300.
[0074] For example, when the expansion unit 330 of this embodiment
is intended to be appropriately expanded at the high-pressure side
pressure PHr=2.3 MPa and at the expansion ratio=2.0, it is
necessary to set the low-pressure side pressure PLr at 1.15 MPa,
and the appropriate expansion unit pressure difference .DELTA.Po
for the appropriate expansion at 1.15 MPa. When the expansion unit
pressure difference .DELTA.P is smaller than the appropriate
expansion unit pressure difference .DELTA.Po, the expansion unit
330 is over-expanded. As the expansion unit pressure difference
.DELTA.P is decreased, the operation of the Rankine cycle 300
becomes more unstable. When the expansion unit pressure difference
.DELTA.P is larger than an appropriate expansion unit pressure
difference .DELTA.Po, the expansion of the expansion unit 330 is
insufficient. Thus, the minimum expansion unit pressure difference
.DELTA.P without an unstable operation of the Rankine cycle 300 is
set as the predetermined pressure difference .DELTA.Pa. Under the
above-mentioned condition, for example, the predetermined pressure
difference .DELTA.Pa is set to 0.8 Mpa (.DELTA.Pa=0.8 Mpa) (which
corresponds to 70% level of the appropriate expansion unit pressure
difference .DELTA.Po).
[0075] When the expansion unit pressure difference .DELTA.P is
determined to be smaller than the predetermined pressure difference
.DELTA.Pa in step S130, it is determined whether or not the number
of revolutions of the present expansion unit 330 is the minimum
operable number of revolutions in step S140. The number of
revolutions of the expansion unit which is equal to the number of
revolutions of the electric generator 331 is detected by the
inverter 51.
[0076] When the number of revolutions of the expansion unit is
determined not to be the minimum number of revolutions in step
S140, the number of revolutions of the expansion unit 330 can be
decreased, and the energization control circuit 50 decreases the
number of revolutions of the expansion unit 330 only by a
predetermined amount. In decreasing the number of revolutions of
the expansion unit 330, electric current is supplied from the
inverter 51 to the electric generator 331 during generation of
electricity to provide a braking effect.
[0077] When the number of revolutions of the expansion unit is
decreased in step S150, a resistance effect to the RA refrigerant
in the expansion unit 330 is enhanced to decrease a low-pressure
side pressure PLr, thereby increasing the expansion unit pressure
difference .DELTA.P. Thus, by repeating of the above-mentioned
steps S110 to 150, the expansion unit pressure difference .DELTA.P
is controlled such that the pressure difference .DELTA.P is equal
to or more than the predetermined pressure difference
.DELTA.Pa.
[0078] If the determination of step S140 is NO, that is, when the
number of revolutions of the expansion unit is determined to be
already the minimum number of revolutions in step S140, the
expansion unit pressure difference .DELTA.P cannot be controlled so
as to be equal to or more than the predetermined pressure
difference .DELTA.Pa as mentioned above. In this case, the Rankine
cycle 300 is stopped for the purpose of safety in step S160. If the
determination of step S130 is NO, that is, when the expansion unit
pressure difference .DELTA.P is determined to be larger than the
predetermined pressure difference .DELTA.Pa, the control of the
number of revolutions of the expansion unit 330 is unnecessary, and
the operation returns to a step S100.
[0079] As mentioned above, in this embodiment, the AC condenser 220
and the RA condenser 340 dedicated are respectively set in the
refrigeration cycle 200 and the Rankine cycle 300, and the AC
condenser 220 is disposed on the front side of the RA condenser 340
(on the upstream side of the flow of the cooling air). Thus,
regardless of the presence or absence of the operation of the
Rankine cycle 300, the AC condenser 220 constantly allows an
external fluid whose temperature is equal to the temperature of
outside air to flow thereinto. In operation of the refrigeration
cycle 200, this does not lead to reduction in reliability on the
refrigeration cycle 200 together with deterioration of power of the
compressor 210, as well as a decrease in refrigeration capacity
together with a decrease in coefficient of performance.
[0080] In singly operating of the Rankine cycle 300, the respective
cycles 200 and 300 form the independent refrigerant circuits, so
that the Rankine cycle 300 can exhibit a sufficient inherent
capacity, while ensuring reliability of the expansion unit 330 and
the pump 310 without storing the refrigerant and lubricating oil
from the Rankine cycle 300 into the refrigeration cycle 200.
[0081] This can ensure the reliability of both the Rankine cycles
200 and 300, and provide the refrigeration apparatus 100A that can
exhibit the sufficient performance as a whole.
[0082] In the simultaneous operation of the refrigeration cycle 200
and the Rankine cycle 300, the number of revolutions of the
expansion unit 330 is decreased such that the expansion unit
pressure difference .DELTA.P is equal to or more than the
predetermined pressure difference .DELTA.Pa. This can ensure the
sufficient expansion unit pressure difference .DELTA.P to prevent
the unstable operation of the Rankine cycle 300, while obtain the
sufficient amount of electricity generated by the expansion unit
330.
[0083] The calculation of the expansion unit pressure difference
.DELTA.P can be performed easily and surely by use of pressure
values detected by two pressure sensors 301 and 302.
[0084] The positions of the inlet 220a and outlet 220b of the AC
condenser 220 are positioned in the same respective areas as those
of the inlet 340a and outlet 340b of the RA condenser 340 as viewed
from the flow direction of the cooling air. Thus, the inflow area
and outflow area for the AC refrigerant in the AC condenser 220 can
have the same positional relationship as that of the inflow area
and outflow area for the RA refrigerant in the RA condenser 340.
The amount of increase in temperature of cooling air passing
through the AC condenser 220 is high on the inlet side of the AC
refrigerant, and becomes lower toward the outflow side. It is
apparent that the temperature of the RA refrigerant in the RA
condenser 340 becomes lower from the inflow side toward the outflow
side by the heat exchange. This can provide such a positional
relationship that the temperature distribution of the cooling air
flowing into the RA condenser 340 has the same tendency as that of
the RA refrigerant into the RA condenser 340. Thus, the difference
in temperature between the cooling air and the RA refrigerant can
be entirely made uniform, and thereby it is possible to effectively
radiate heat from the RA condenser 340.
[0085] The inlet 220a and outlet 220b of the AC condenser 220 are
opened toward the front side. Thus, it is not necessary to dispose
piping between the AC condenser 220 and the RA condenser 340 in
routing piping for the AC refrigerant to the AC condenser 220. This
does not degrade a dimensional accuracy between both condensers 220
and 340, and can facilitate connection of the piping to the AC
condenser 220.
[0086] The inlet 340a and outlet 340b of the RA condenser 340 are
opened in the direction perpendicular to the flow direction of the
cooling air. Thus, it is not necessary to dispose piping between
the AC condenser 220 and the RA condenser 340, or to dispose piping
from the front side to the rear side in routing piping for the RA
refrigerant to the RA condenser 340. Accordingly, it can prevent
degradation of a dimensional accuracy between both the condensers
220 and 340, or a decrease in area of the front surface of the AC
condenser 220. Further, this can also facilitate connection of the
piping to the RA condenser 340.
[0087] In control of preventing a decrease in pressure difference
based on a flowchart 1 shown in FIG. 6, after the number of
revolutions of the expansion unit 330 is controlled such that the
expansion unit pressure difference .DELTA.P is equal to or more
than the predetermined pressure difference .DELTA.Pa, the number of
revolutions of the expansion unit 330 may be preferably controlled
such that the expansion unit pressure difference .DELTA.P becomes
the appropriate pressure difference .DELTA.Po. Thus, it can
constantly obtain the optimal amount of electricity generated.
Second Embodiment
[0088] FIGS. 7 and 8 show a second embodiment of the invention. The
second embodiment differs from the first embodiment in a method of
calculating an expansion unit pressure difference .DELTA.P.
[0089] A refrigeration apparatus 100B of the second embodiment has
the same basic structure as that of the refrigeration apparatus
100A of the first embodiment. As shown in FIG. 7, the pressure
sensor 302 is omitted, and the refrigeration apparatus 100B is
provided with a temperature sensor (corresponding to an air
temperature detection means in the invention) 101 for detecting the
temperature of cooling air passing between the AC condenser 220 and
the RA condenser 340 (a passing air temperature Tas). A temperature
signal (passing air temperature Tas) detected by the temperature
sensor 101 is output to the energization control circuit 50.
[0090] In a flowchart 2 for controlling prevention of a decrease in
pressure difference, as shown in FIG. 8, steps S110 and S120 in the
flowchart 1 shown in FIG. 6 and explained in the first embodiment
are changed into steps S111 and S121, respectively, and a step S115
is added to between steps S111 and S121.
[0091] Now, the control of prevention of the decrease in pressure
difference based on the flowchart 2 will be described below. That
is, when the refrigeration cycle 200 and the Rankine cycle 300 are
simultaneously driven and operated in step S100, the energization
control circuit 50 reads a high-pressure side pressure PHr detected
by the pressure sensor 301 and a passing air temperature Tas
detected by the temperature sensor 101 in step S11.
[0092] In step S115, the low-pressure side pressure PLr is
calculated. The outline of the calculation will be described below.
The step S115 corresponds to calculation means for calculating the
low-pressure side pressure PLr.
[0093] First, an amount of heat Qir absorbed by the heater 220 from
the coolant is estimated. When .PHI.h is a temperature efficiency
of the heater 220, CW is a specific heat of the coolant, Gw is a
flow rate by weight of the coolant, Tw is a temperature of the
coolant, and THr is a temperature of the RA refrigerant at the
heater 220, the following equation can be represented:
Qir=.PHI.hCwGw(Tw-THr)
[0094] Next, in the Rankine cycle 300, when Qor is an amount of
heat radiation at the RA radiator 340 which is balanced with an
amount of heat Qir absorbed at the heater 32, the following
equation can be estimated:
Qor=AQir
wherein A is a coefficient corresponding to a driving force of the
expender 330, for example, 0.9 (A=0.9).
[0095] Further, when .PHI.cr is a temperature efficiency of the RA
condenser 340, Ca is a specific heat of the cooling air, Ga is a
flow rate by weight of the cooling air, TLr is a temperature of the
RA refrigerant at the RA condenser 340, and Tas is a temperature of
the cooling air flowing into the RA condenser 340, that is, a
passing air temperature, the following equation can be
represented:
Qor=.PHI.crCaGa(TLr-Tas)
[0096] Accordingly, the following formula (1) can be obtained:
A.PHI.hCwGw(Tw-THr)=.PHI.crCaGa(TLr-Tas) (1)
[0097] The temperature efficiency .PHI.h is determined according to
set specifications of the heater 220. The coolant specific heat Cw
is determined as a value of a physical property of the coolant. The
flow rate by weight of the coolant Gw can be estimated from the
number of revolutions of the warm water pump 22. The temperature of
the coolant Tw can be determined using temperature data of the
coolant associated with engine control. The RA refrigerant THr can
be estimated from the high-pressure side pressure value (PHr) read
in step S111.
[0098] The temperature efficiency .PHI.r is determined according to
set specifications of the RA condenser 340. The cooling air
specific heat Ca is determined as a value of a physical property of
the air. The flow rate by weight of the cooling air Ga can be
estimated from the vehicle speed, and an operating state of the
electric fan 260. As the passing air temperature Tas, a value read
in step S111 is used.
[0099] Thus, the RA refrigerant temperature TLr can be calculated
from the formula (1) and the above-mentioned condition. Further, a
low-pressure side pressure PLr at the RA condenser 340 can be
calculated from the thus-obtained RA refrigerant temperature
TLr.
[0100] In step S121, an expansion unit pressure difference .DELTA.P
is calculated by subtracting the low-pressure side pressure PLr
calculated in step S115 from the high-pressure side pressure PHr
read in step S111.
[0101] As mentioned above, the execution of steps S130 to S160 can
perform control for preventing a decrease in pressure difference,
like the first embodiment, thereby obtaining the same effects as
those of the first embodiment.
[0102] In the second embodiment, the low-pressure side pressure
calculation means of step S115 is provided, so that the pressure
sensor 302 can calculate the expansion unit pressure difference
.DELTA.P, instead of the temperature sensor 101.
Third Embodiment
[0103] FIGS. 9 and 10 show a third embodiment of the invention. The
third embodiment differs from the first embodiment in a method of
calculating an expansion unit pressure difference .DELTA.P, like
the second embodiment.
[0104] A refrigeration apparatus 100C of the third embodiment has
the same basic structure as that of the refrigeration apparatus
100A of the first embodiment. As shown in FIG. 9, the pressure
sensor 302 is omitted, and the refrigeration apparatus 100C is
provided with a temperature sensor (corresponding to inflow air
temperature detection means in the invention) 102 for detecting the
temperature of cooling air flowing into the AC condenser 220
(inflow air temperature Ta). A temperature signal (inflow air
temperature Ta) detected by the temperature sensor 102 is output to
the energization control circuit 50.
[0105] In a flowchart 3 for controlling prevention of a decrease in
pressure difference, as shown in FIG. 10, steps S110 and S120 in
the flowchart 1 shown in FIG. 6 and explained in the first
embodiment are changed into steps S112 and S122, respectively, and
step S116 is added to between the steps S112 and S122.
[0106] Now, the control of prevention of the decrease in pressure
difference based on the flowchart 3 will be described below. That
is, when the refrigeration cycle and the Rankine cycle are
simultaneously driven in step S100, the energization control
circuit 50 reads a high-pressure side pressure PHr detected by the
pressure sensor 301 and an inflow air temperature Ta detected by
the temperature sensor 102 in step S112.
[0107] In step S116, a low-pressure side pressure PLr is
calculated. The outline of the calculation will be described below.
Step S116 corresponds to calculation means for calculating the
low-pressure side pressure PLr.
[0108] In the refrigeration cycle 200, first, when Qoa is a
necessary refrigeration capacity, that is, an amount of heat
radiation at the AC condenser 220 which is balanced with an amount
of heat absorbed Qia at the evaporator 250, the following equation
can be estimated:
BQoa=Qia
wherein B is a coefficient corresponding to a driving force of the
compressor 210, for example, 0.7 (B=0.7).
[0109] Further, when .PHI.ca is a temperature efficiency of the AC
condenser 220, Ca is a specific heat of the cooling air, Ga is a
flow rate by weight of the cooling air, Tas is a passing air
temperature of the cooling air after passing through the AC
condenser 220, and Ta is a temperature of the air flowing into the
AC condenser 220, the following equation can be represented:
Qoa=.PHI.caCaGa(Tas-Ta)
[0110] Accordingly, the following formula (2) can be obtained:
B.PHI.caCaGa(Tas-Ta)=.PHI.ia (2)
[0111] The temperature efficiency .PHI.ca is determined according
to set specifications of the AC condenser 220. The coolant specific
heat Ca is determined as a value of a physical property of the air.
The flow rate by weight of the cooling air Ga can be estimated from
a vehicle speed and an operating state of the electric fan 260. As
the inflow air temperature Ta, a value read in step S112 is used.
The amount of absorbed heat Qia is calculated from an environmental
condition and a set temperature set by a passenger.
[0112] Thus, the passing air temperature Tas can be calculated from
the formula (2) and the above-mentioned condition.
[0113] Using the passing air temperature Tas calculated above, the
same computation as that in step S115 of the second embodiment can
be performed to calculate the low-pressure side pressure PLr.
[0114] Then, in step S122, the expansion unit pressure difference
.DELTA.P is calculated by subtracting the low-pressure side
pressure PLr calculated in step S116 from the high-pressure side
pressure PHr read in step S112.
[0115] As mentioned above, the execution of steps S130 to S160 can
perform control for preventing a decrease in pressure difference,
like the first embodiment, thereby obtaining the same effects as
those of the first embodiment.
[0116] In the third embodiment, the low-pressure side pressure
calculation means of step S116 is provided, so that the pressure
sensor 302 can calculate the expansion unit pressure difference
.DELTA.P, instead of the temperature sensor 102.
Fourth Embodiment
[0117] FIG. 11 shows a fourth embodiment of the invention. In the
fourth embodiment, ducts 103 serving as an introduction flow path,
and guides 104 serving as an opening adjustment portion are
provided relative to the AC condenser 220 and the RA condenser 340
of the first to third embodiments.
[0118] The ducts 103 each of which is a plate-like member adapted
for introduction of air are provided on both ends of the RA
condenser 340 in the vehicle width direction. The ducts 103 are
formed so as to expand from both ends of the RA condenser 340 to
the front side of the AC condenser 220. As indicated by the dashed
arrow in FIG. 11, the ducts 103 are formed so as to allow cooling
air to be directly introduced into the RA condenser 340 through
between the AC condenser 220 and the RA condenser 340 on both ends
without allowing the cooling air to pass from the front side of the
AC condenser 220 through the AC condenser 220.
[0119] The guides 104 each of which is formed as a plate-like
member are disposed on both ends of the AC condenser 220 in the
vehicle width direction and adapted to be rotatably operated around
the respective ends in the vehicle width direction by the
energization control circuit 50. As indicated by the solid arrow in
FIG. 11, when the guide 104 is rotated toward the outside in the
vehicle width direction, an area of an opening to the AC condenser
220 is enlarged to increase an amount of inflow of the cooling air
into the AC condenser 220. In contrast, as indicated by the dashed
arrow in FIG. 11, when the guide 104 is rotated toward the inside
in the vehicle width direction, an area of opening in a flow path
formed by the duct 103, that is, a flow path directed toward
between the AC condenser 220 and the RA condenser 340 is enlarged
to increase an amount of inflow of the cooling air into the RA
condenser 340.
[0120] In the fourth embodiment thus obtained, the position of
rotation of the guide 104 is controlled by the energization control
circuit 50 according to a necessary amount of heat radiated from
each of the AC condenser 220 and the RA condenser 340. In other
words, in singly operating of the refrigeration cycle 200, the
guides 104 are controlled to be rotated according to the necessary
amount of heat radiated from the AC condenser 220. The rotating of
the guide 104 toward the outside in the vehicle width direction
increases an amount of inflow of the cooling air into the AC
condenser 220, thereby enabling improvement of heat radiation
characteristics of the AC condenser 220. At this time, the guide
104 can prevent the cooling air having passed through the AC
condenser 220 from flowing again into the AC condenser 220.
[0121] In singly operating of the Rankine cycle, the guides 104 are
controlled to be rotated according to the necessary amount of heat
radiated from the RA condenser 340. The rotating of the guide 104
toward the inside in the vehicle width direction increases an
amount of inflow of the cooling air into the RA condenser 340
without receiving resistance of the AC condenser 220, thereby
enabling improvement of heat radiation performance of the RA
condenser 340.
[0122] Furthermore, in simultaneously operating the refrigeration
cycle and the Rankine cycle, the guides 104 are controlled to be
rotated according to the necessary amount of heat radiated from
both condensers 220 and 340. In this case, the guides 104 are
rotated toward the inside in the vehicle width direction, thus
allowing the cooling air whose temperature is the same as that of
the outside air to flow into the RA condenser 340, thereby
improving the heat radiation performance at the RA condenser
340.
[0123] In this way, the amounts of inflow of the cooling air into
the condensers 220 and 340 are adjusted according to the respective
necessary amounts of heat radiated from the AC condenser 220 and
the RA condenser 340, thereby enabling effective heat radiation at
each of the condensers 220 and 340.
Fifth Embodiment
[0124] FIGS. 12 and 13 show a fifth embodiment of the invention. In
the fifth embodiment, an area of a front surface of the AC
condenser 220 is set to be smaller than that of a front surface of
the RA condenser 340 so as to form an area (e.g., an A area shown
in FIGS. 12 and 13) where both condensers 220 and 340 are not
overlapped with each other.
[0125] The dimension in the vertical direction of the AC condenser
220 is smaller than that of the RA condenser 340, which forms the
area where both condensers 220 and 340 are not superimposed on each
other on the lower side of the AC condenser 220.
[0126] If the dimension in the vertical direction of the AC
condenser 220 is simply decreased, the heat radiation capacity of
the AC condenser 220 may become small. Thus, as shown in FIG. 13, a
thickness dimension D of a heat exchanging portion (a dimension in
the flow direction of the cooling air) is set larger than that of a
heat exchanging portion of the RA condenser 340 to ensure the heat
radiation capacity.
[0127] Thus, the cooling air which is not subjected to the heat
exchange at the AC condenser 220 and whose temperature is equal to
that of the outside air can directly flow into the RA condenser
340, thereby improving the heat radiation capacity of the RA
condenser 340.
[0128] The thickness dimension D of the heat exchanging portion is
increased by a decrease in area of the front surface of the AC
condenser 220 to obtain the heat radiation capacity. This
facilitates reduction in area of the front surface of the AC
condenser 220.
Other Embodiments
[0129] Although the present invention has been fully described in
connection with the preferred embodiments thereof with reference to
the accompanying drawings, it is to be noted that various changes
and modifications will become apparent to those skilled in the
art.
[0130] For example, set positions of the pressure sensors 301 and
302 in the Rankine cycle 300 are not limited to those described in
the first embodiment. The pressure sensor 301 may be positioned in
any high-pressure side area. The pressure sensor 301 may be
preferably provided between the pump. 310 and the heater 320. The
pressure sensor 302 may be positioned in the low-pressure side
area. The pressure sensor 302 may be preferably provided between
the RA condenser 340 and the pump 310.
[0131] Set positions and opening directions of the inlets 220a and
340a and the outlets 220b and 340b of the AC condenser 220 and the
RA condenser 340 are not limited to the contents described in each
of the above-mentioned embodiments, and may be any other position
and direction.
[0132] The compressor 210 in the refrigeration cycle 200 is not
limited to an engine-driving compressor driven by the engine 10,
and also may be an electric compressor driven by an electric motor,
or a hybrid compressor driven by an engine and an electric
motor.
[0133] In the Rankine cycle 300, the pump 310 is driven by the
electric motor 311, and the electric generator 331 is connected to
the expansion unit 330. Alternatively, the electric motor 311 may
be omitted, and the electric generator 331 may serve as a motor
generator having both functions of an electric motor and an
electric generator. The pump 310 and the expansion unit 330 may be
connected to the motor generator.
[0134] In this case, in operating of the Rankine cycle 300, first,
the motor generator acts as an electric motor to drive the pump
310. When exhaust heat is sufficiently obtained from the engine 10
and the driving force at the expansion unit 330 exceeds the power
of the pump 310, the motor generator acts as an electric generator
for generating electricity.
[0135] This can eliminate a driving source dedicated to drive the
pump 310 (the electric motor 311 in each of the above-mentioned
embodiments), thereby simplifying the structure of the cycle, while
decreasing energy for operating the pump 310.
[0136] Such changes and modifications are to be understood as being
within the scope of the present invention as defined by the
appended claims.
* * * * *