U.S. patent application number 11/794319 was filed with the patent office on 2008-05-15 for refrigerating apparatus.
This patent application is currently assigned to DAIKIN INDUSTRIES, LTD.. Invention is credited to Azuma Kondo, Kazuyoshi Nomura, Yoshinari Oda, Satoru Sakae, Masaaki Takegami, Kenji Tanimoto.
Application Number | 20080110199 11/794319 |
Document ID | / |
Family ID | 36614801 |
Filed Date | 2008-05-15 |
United States Patent
Application |
20080110199 |
Kind Code |
A1 |
Takegami; Masaaki ; et
al. |
May 15, 2008 |
Refrigerating Apparatus
Abstract
The loss of refrigerant pressure which is caused in a
return-side interconnecting piping line (19) comprising return-side
interconnecting piping lines respectively extending from outlet
ports (24, 34, 44) of single-stage side utilization units (12, 13,
14) to an inlet port (61) of a heat source unit (11) is set such
that the lowest valued refrigerant pressure loss is caused by a
said return-side interconnecting piping line of the return-side
interconnecting piping line (19) that is connected to the lowest of
the single-stage side utilization units (12, 13, 14) in compartment
preset temperature.
Inventors: |
Takegami; Masaaki; (Osaka,
JP) ; Sakae; Satoru; (Osaka, JP) ; Tanimoto;
Kenji; (Osaka, JP) ; Nomura; Kazuyoshi;
(Osaka, JP) ; Oda; Yoshinari; (Osaka, JP) ;
Kondo; Azuma; (Osaka, JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
DAIKIN INDUSTRIES, LTD.
Osaka-shi, Osaka
JP
|
Family ID: |
36614801 |
Appl. No.: |
11/794319 |
Filed: |
December 22, 2005 |
PCT Filed: |
December 22, 2005 |
PCT NO: |
PCT/JP05/23585 |
371 Date: |
June 27, 2007 |
Current U.S.
Class: |
62/498 |
Current CPC
Class: |
F25B 2400/22 20130101;
F25B 2500/01 20130101; F25B 5/02 20130101 |
Class at
Publication: |
62/498 |
International
Class: |
F25B 1/00 20060101
F25B001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 28, 2004 |
JP |
2004-381015 |
Oct 18, 2005 |
JP |
2005-303502 |
Claims
1. A refrigerating apparatus comprising: (a) a plurality of
single-stage side utilization units (12, 13, 14) having cooling
heat exchangers (21, 31, 41) respectively, each of the cooling heat
exchangers (21, 31, 41) being configured to provide cooling of its
associated compartment so that the associated compartment is kept
at a predetermined preset temperature, and (b) a single heat source
unit (11) having a compressor (29), wherein in a refrigerant
circuit (20) in which the single-stage side utilization units (12,
13, 14) are connected in parallel with the heat source unit (11) by
interconnecting piping lines (18, 19) refrigerant is circulated
between each of the single-stage side utilization units (12, 13,
14) and the heat source unit (11) whereby single-stage compression
refrigeration cycles are performed, wherein the loss of pressure of
the refrigerant which is caused in the return-side interconnecting
piping line (19) comprising return-side interconnecting piping
lines respectively extending from outlet ports (24, 34, 44) of the
single-stage side utilization units (12, 13, 14) to an inlet port
(61) of the heat source unit (11) is set such that the lowest
valued refrigerant pressure loss is caused by a said return-side
interconnecting piping line that is connected to the lowest of the
single-stage side utilization units (12, 13, 14) in compartment
preset temperature.
2. A refrigerating apparatus comprising: (a) a plurality of
single-stage side utilization units (12, 13, 14) having cooling
heat exchangers (21, 31, 41) respectively, each of the cooling heat
exchangers (21, 31, 41) being configured to provide cooling of its
associated compartment so that the associated compartment is kept
at a predetermined preset temperature, and (b) a single heat source
unit (11) having a compressor (29), wherein in a refrigerant
circuit (20) in which the single-stage side utilization units (12,
13, 14) are connected in parallel with the heat source unit (11) by
interconnecting piping lines (18, 19) refrigerant is circulated
between each of the single-stage side utilization units (12, 13,
14) and the heat source unit (11) whereby single-stage compression
refrigeration cycles are performed, wherein the loss of pressure of
the refrigerant which is caused in the return-side interconnecting
piping line (19) comprising return-side interconnecting piping
lines respectively extending from outlet ports (24, 34, 44) of the
single-stage side utilization units (12, 13, 14) to an inlet port
(61) of the heat source unit (11) is set such that the aforesaid
refrigerant pressure loss becomes smaller as the compartment preset
temperature in the single-stage side utilization units (12, 13, 14)
connected respectively by the aforesaid return-side interconnecting
piping lines to the inlet port (61) of the heat source unit (11)
becomes lower.
3. A refrigerating apparatus comprising: (a) a plurality of
single-stage side utilization units (12, 13, 14) having cooling
heat exchangers (21, 31, 41) respectively, each of the cooling heat
exchangers (21, 31, 41) being configured to provide cooling of its
associated compartment so that the associated compartment is kept
at a predetermined preset temperature, and (b) a single heat source
unit (11) having a compressor (29), wherein in a refrigerant
circuit (20) in which the single-stage side utilization units (12,
13, 14) are connected in parallel with the heat source unit (11) by
interconnecting piping lines (18, 19) refrigerant is circulated
between each of the single-stage side utilization units (12, 13,
14) and the heat source unit (11) whereby single-stage compression
refrigeration cycles are performed, wherein the length of
return-side interconnecting piping lines respectively extending
from outlet ports (24, 34, 44) of the single-stage side utilization
units (12, 13, 14) to an inlet port (61) of the heat source unit
(11) is set such that a said return-side interconnecting piping
line that is connected to the lowest of the single-stage side
utilization units (12, 13, 14) in compartment preset temperature is
the shortest return-side interconnecting piping line.
4. A refrigerating apparatus comprising: (a) a plurality of
single-stage side utilization units (12, 13, 14) having cooling
heat exchangers (21, 31, 41) respectively, each of the cooling heat
exchangers (21, 31, 41) being configured to provide cooling of its
associated compartment so that the associated compartment is kept
at a predetermined preset temperature, and (b) a single heat source
unit (11) having a compressor (29), wherein in a refrigerant
circuit (20) in which the single-stage side utilization units (12,
13, 14) are connected in parallel with the heat source unit (11) by
interconnecting piping lines (18, 19) refrigerant is circulated
between each of the single-stage side utilization units (12, 13,
14) and the heat source unit (11) whereby single-stage compression
refrigeration cycles are performed, wherein the length of
return-side interconnecting piping lines respectively extending
from outlet ports (24, 34, 44) of the single-stage side utilization
units (12, 13, 14) to an inlet port (61) of the heat source unit
(11) is set such that the aforesaid length becomes shorter as the
compartment preset temperature in the single-stage side utilization
units (12, 13, 14) connected respectively by the aforesaid
return-side interconnecting piping lines to the inlet port (61) of
the heat source unit (11) becomes lower.
5. The refrigerating apparatus of any one of claims 1-4, wherein in
the return-side interconnecting piping line (19) composed of the
return-side interconnecting piping lines establishing respective
connections between the outlet ports (24, 34, 44) of the
single-stage side utilization units (12, 13, 14) and the inlet port
(61) of the heat source unit (11) the lowest of the single-stage
side utilization units (12, 13, 14) in compartment preset
temperature is connected at the most downstream side.
6. The refrigerating apparatus of claim 5, wherein in the
supply-side interconnecting piping line (18) composed of
supply-side interconnecting piping lines establishing respective
connections between an outlet port (71) of the heat source unit
(11) and inlet ports (23, 33, 43) of the single-stage side
utilization units (12, 13, 14) the lowest of the single-stage side
utilization units (12, 13, 14) in compartment preset temperature is
connected at the most upstream side.
7. The refrigerating apparatus of any one of claims 1-4, wherein
said refrigerating apparatus further includes a two-stage side
circuit (47) in which a two-stage side utilization unit (15) having
a cooling heat exchanger (51) configured to provide cooling of its
associated compartment so that the associated compartment is kept
at a predetermined preset temperature and a booster compressor (46)
are connected in series; wherein in the refrigerant circuit (20)
the two-stage side circuit (47) is, together with the single-stage
side utilization units (12, 13, 14), connected in parallel with the
heat source unit (11) by the interconnecting piping lines (18, 19)
and the refrigerant is circulated between the two-stage side
utilization unit (15) and the heat source unit (11) whereby
two-stage compression refrigeration cycles are performed.
8. The refrigerating apparatus of claim 7, wherein the two-stage
side circuit (47) is connected at the most upstream side in the
return-side interconnecting piping line (19) composed of the
return-side interconnecting piping lines establishing respective
connections between (i) the outlet ports (24, 34, 44) of the
single-stage side utilization units (12, 13, 14) and an outlet port
(54) of the two-stage side circuit (47) and (ii) the inlet port
(61) of the heat source unit (11).
9. The refrigerating apparatus of claim 8, wherein the two-stage
side circuit (47) is connected at the most upstream side in the
supply-side interconnecting piping line (18) composed of the
supply-side interconnecting piping lines establishing respective
connections between (i) the outlet port (71) of the heat source
unit (11) and (ii) the inlet ports (23, 33, 43) of the single-stage
side utilization units (12, 13, 14) and an inlet port (53) of the
two-stage side circuit (47).
Description
TECHNICAL FIELD
[0001] This invention relates to a refrigerating apparatus in which
a plurality of utilization units are connected in parallel with a
heat source unit.
BACKGROUND ART
[0002] For many years, a refrigerating apparatus of the type, in
which a plurality of utilization units are connected in parallel
with a single heat source unit, has been known in the art. For
example, such a type of refrigerating apparatus is installed in a
convenience store and provides cold storage and freeze storage in
showcases in the store. In this refrigerating apparatus, the heat
source unit is equipped with a compressor and a heat source-side
heat exchanger while on the other hand each of the utilization
units is provided with a cooling heat exchanger and an expansion
valve. The utilization units are connected to the heat source unit
by interconnecting piping lines. In each of the utilization units,
the temperature at which refrigerant becomes evaporated in the
cooling heat exchanger is set depending on the compartment preset
temperature of the showcases.
[0003] JP-A-2003-314909 discloses a refrigerating apparatus which
is of the above-described type. In this patent document, FIG. 1
thereof shows a refrigerating apparatus in which three indoor units
(utilization units) are connected in parallel with a single outdoor
unit (heat source unit). Two of the three indoor units are cold
storage units and the rest is a freeze storage unit, and a booster
unit provided with a compressor is connected in series with the
freeze storage unit.
DISCLOSURE OF THE INVENTION
Problems which the Invention Seeks to Overcome
[0004] Incidentally, in the case where such a refrigerating
apparatus is installed in a commercial facility such as a
convenience store, the decision on where to place a heat source
unit and utilization units is made mainly by the layout of the
facility as well as by the style of service. And the length of
interconnecting piping lines from the outlet ports of the
utilization units to the inlet port of the heat source unit is
determined by the layout of the heat source unit as well as by the
layout of the utilization units.
[0005] Accordingly, in some cases, the length of an interconnecting
piping line extending from the outlet port of one utilization unit
of lower compartment preset temperature to the inlet port of the
heat source unit may become longer than the other utilization unit
of higher compartment preset temperature. In such a case, there is
the possibility that the loss of refrigerant pressure which is
caused in the return-side interconnecting piping lines respectively
extending from the outlet ports of the utilization units to the
inlet port of the heat source unit becomes higher in one
utilization unit of lower compartment preset temperature than in
the other utilization unit of higher compartment preset
temperature.
[0006] At this time, both the refrigerant pressure at the outlet
ports of the utilization units and the refrigerant evaporative
pressure in the utilization units become higher in the one
utilization unit of lower compartment preset temperature than in
the other utilization unit of higher compartment preset
temperature. Consequently, the refrigerant evaporative temperature
in the one utilization unit (at lower compartment preset
temperature) becomes higher than in the other utilization unit (at
higher compartment preset temperature). This therefore gives rise
the possibility that in a conventional refrigerating apparatus the
refrigerant evaporative temperature in a certain utilization unit
does not correspond to the compartment preset temperature.
[0007] With the above-described problems with the conventional
techniques in mind, the present invention was devised. Accordingly,
a general object of the present invention is to make the
refrigerant evaporative temperature in a utilization unit in a
refrigerating apparatus appropriate with respect to the compartment
preset temperature of the utilization unit to thereby aim at
accomplishing improvement in the efficiency of the refrigerant
apparatus.
Means for Overcoming the Problems
[0008] The present invention provides, as first to fourth aspects,
refrigerating apparatuses (30) each of which comprises: (a) a
plurality of single-stage side utilization units (12, 13, 14)
having cooling heat exchangers (21, 31, 41) respectively, each of
the cooling heat exchangers (21, 31, 41) being configured to
provide cooling of its associated compartment so that the
associated compartment is kept at a predetermined preset
temperature, and (b) a single heat source unit (11) having a
compressor (29), wherein in a refrigerant circuit (20) in which the
single-stage side utilization units (12, 13, 14) are connected in
parallel with the heat source unit (11) by interconnecting piping
lines (18, 19) refrigerant is circulated between each of the
single-stage side utilization units (12, 13, 14) and the heat
source unit (11) whereby single-stage compression refrigeration
cycles are performed.
[0009] In the refrigerating apparatus (30) of the first aspect, the
loss of pressure of the refrigerant which is caused in the
return-side interconnecting piping line (19) comprising return-side
interconnecting piping lines respectively extending from outlet
ports (24, 34, 44) of the single-stage side utilization units (12,
13, 14) to an inlet port (61) of the heat source unit (11) is set
such that the lowest valued refrigerant pressure loss is caused by
a said return-side interconnecting piping line that is connected to
the lowest of the single-stage side utilization units (12, 13, 14)
in compartment preset temperature.
[0010] In the refrigerating apparatus (30) of the second aspect,
the loss of pressure of the refrigerant which is caused in the
return-side interconnecting piping line (19) comprising return-side
interconnecting piping lines respectively extending from outlet
ports (24, 34, 44) of the single-stage side utilization units (12,
13, 14) to an inlet port (61) of the heat source unit (11) is set
such that the aforesaid refrigerant pressure loss becomes smaller
as the compartment preset temperature in the single-stage side
utilization units (12, 13, 14) connected respectively by the
aforesaid return-side interconnecting piping lines to the inlet
port (61) of the heat source unit (11) becomes lower.
[0011] In the refrigerating apparatus (30) of the third aspect, the
length of return-side interconnecting piping lines respectively
extending from outlet ports (24, 34, 44) of the single-stage side
utilization units (12, 13, 14) to an inlet port (61) of the heat
source unit (11) is set such that a said return-side
interconnecting piping line that is connected to the lowest of the
single-stage side utilization units (12, 13, 14) in compartment
preset temperature is the shortest return-side interconnecting
piping line.
[0012] In the refrigerating apparatus (30) of the fourth aspect,
the length of return-side interconnecting piping lines respectively
extending from outlet ports (24, 34, 44) of the single-stage side
utilization units (12, 13, 14) to an inlet port (61) of the heat
source unit (11) is set such that the aforesaid length becomes
shorter as the compartment preset temperature in the single-stage
side utilization units (12, 13, 14) connected respectively by the
return-side interconnecting piping lines to the inlet port (61) of
the heat source unit (11) becomes lower.
[0013] The present invention provides, as a fifth aspect according
to any one of the first to fourth aspects, a refrigerating
apparatus in which in the return-side interconnecting piping line
(19) composed of the return-side interconnecting piping lines
establishing respective connections between the outlet ports (24,
34, 44) of the single-stage side utilization units (12, 13, 14) and
the inlet port (61) of the heat source unit (11) the lowest of the
single-stage side utilization units (12, 13, 14) in compartment
preset temperature is connected at the most downstream side.
[0014] The present invention provides, as a sixth aspect according
to the fifth aspect, a refrigerating apparatus in which in the
supply-side interconnecting piping line (18) composed of
supply-side interconnecting piping lines establishing respective
connections between an outlet port (71) of the heat source unit
(11) and inlet ports (23, 33, 43) of the single-stage side
utilization units (12, 13, 14) the lowest of the single-stage side
utilization units (12, 13, 14) in compartment preset temperature is
connected at the most upstream side.
[0015] The present invention provides, as a seventh aspect
according to any one of the first to sixth aspects, a refrigerating
apparatus in which the refrigerating apparatus further includes a
two-stage side circuit (47) in which a two-stage side utilization
unit (15) having a cooling heat exchanger (51) configured to
provide cooling of its associated compartment so that the
associated compartment is kept at a predetermined preset
temperature and a booster compressor (46) are connected in series,
and in the refrigerant circuit (20) the two-stage side circuit (47)
is, together with the single-stage side utilization units (12, 13,
14), connected in parallel with the heat source unit (11) by the
interconnecting piping lines (18, 19) and the refrigerant is
circulated between the two-stage side utilization unit (15) and the
heat source unit (11) whereby two-stage compression refrigeration
cycles are performed.
[0016] The present invention provides, as an eighth aspect
according to the seventh aspect, a refrigerating apparatus in which
the two-stage side circuit (47) is connected at the most upstream
side in the return-side interconnecting piping line (19) composed
of the return-side interconnecting piping lines establishing
respective connections between (i) the outlet ports (24, 34, 44) of
the single-stage side utilization units (12, 13, 14) and an outlet
port (54) of the two-stage side circuit (47) and (ii) the inlet
port (61) of the heat source unit (11).
[0017] The present invention provides, as a ninth aspect according
to the eighth aspect, a refrigerating apparatus in which the
two-stage side circuit (47) is connected at the most upstream side
in the supply-side interconnecting piping line (18) composed of the
supply-side interconnecting piping lines establishing respective
connections between (i) the outlet port (71) of the heat source
unit (11) and (ii) the inlet ports (23, 33, 43) of the single-stage
side utilization units (12, 13, 14) and an inlet port (53) of the
two-stage side circuit (47).
OPERATION OF THE INVENTION
[0018] In the first aspect of the present invention, the pressure
of refrigerant at the outlet port (44) of the single-stage side
utilization unit (14) which is the lowest of the single-stage side
utilization units (12, 13, 13) in compartment preset temperature is
the lowest. The evaporative pressure of refrigerant in the
single-stage side utilization units (12, 13, 14) is approximately
equal to the pressure of refrigerant at the outlet ports (24, 34,
44) of the single-stage side utilization units (12, 13, 14). Stated
another way, both the refrigerant evaporative pressure and the
refrigerant evaporative temperature in the single-stage side
utilization units (12, 13, 14) decrease as the refrigerant pressure
at the outlet ports (24, 34, 44) of the single-stage side
utilization units (12, 13, 14) decreases. Consequently, the
refrigerant evaporative temperature in the single-stage side
utilization unit (14) of lowest compartment preset temperature is
the lowest among the refrigerant evaporative temperatures of the
single-stage side utilization units (12, 13, 14).
[0019] In the second aspect of the present invention, the pressure
of refrigerant at the outlet ports (24, 34, 44) of the single-stage
side utilization units (12, 13, 14) becomes lower in ascending
order of the compartment preset temperature. Consequently, both the
refrigerant evaporative pressure and the refrigerant evaporative
temperature in the single-stage side utilization units (12, 13, 14)
also decrease in ascending order of the compartment preset
temperature.
[0020] The loss of refrigerant pressure caused by an
interconnecting piping line is approximately proportional to the
length of the interconnecting piping line. Accordingly, in the
third aspect of the present invention, the loss of refrigerant
pressure which is caused in the return-side interconnecting piping
line (19) composed of the return-side interconnecting piping lines
respectively extending from the outlet ports (24, 34, 44) of the
single-stage side utilization units (12, 13, 14) to the inlet port
(61) of the heat source unit (11) is easily minimized in one of the
return-side interconnecting piping lines that is connected to the
lowest of the single-stage side utilization units (12, 13, 14) in
compartment preset temperature.
[0021] In the fourth aspect of the present invention, the loss of
refrigerant pressure which is caused in the return-side
interconnecting piping line (19) composed of the return-side
interconnecting piping lines respectively extending from the outlet
ports (24, 34, 44) of the single-stage side utilization units (12,
13, 14) to the inlet port (61) of the heat source unit (11) tends
to decrease as the compartment preset temperature in the
single-stage side utilization units (12, 13, 14) connected by the
return-side interconnecting piping lines to the inlet port (61) of
the heat source unit (11) decreases.
[0022] In the fifth aspect of the present invention, the
single-stage side utilization unit (14) of lowest compartment
preset temperature is connected at the most downstream side in the
return-side interconnecting piping line (19), in other words the
single-stage side utilization unit (14) is connected on the near
side from the heat source unit (11).
[0023] In the sixth aspect of the present invention, the
single-stage side utilization unit (14) of lowest compartment
preset temperature which is connected at the most downstream side
in the return-side interconnecting piping line (19) (i.e., on the
near side from the heat source unit (11)) is connected at the most
upstream side in the supply-side interconnecting piping line (18)
(i.e., on the near side from the heat source unit (11)). In other
words, the single-stage side utilization unit (14) of lowest
compartment preset temperature, which is connected in the
return-side interconnecting piping line (19) such that refrigerant
is easily returned to the heat source unit (11) from the
single-stage side utilization unit (14), is connected in the
supply-side interconnecting piping line (18) such that refrigerant
easily flows into the single-stage side utilization unit (14) from
the heat source unit (11). Consequently, when compared to the
single-stage side utilization units (12, 13), more liquid
refrigerant tends to flow into the single-stage side utilization
unit (14) of lowest compartment preset temperature which requires
higher cooling capability than the single-stage side utilization
units (12, 13).
[0024] In the seventh aspect of the present invention, one part of
refrigerant exiting the heat source unit (11) flows into the
single-stage side utilization units (12, 13, 14), becomes
evaporated in the cooling heat exchangers (21, 31, 41), is
thereafter returned back to the heat source unit (11), while on the
other hand the other refrigerant part flows into the two-stage side
utilization unit (15), becomes evaporated in the cooling heat
exchanger (51), is compressed in the booster compressor (46), and
is thereafter returned back to the heat source unit (11).
Accordingly, the refrigerant from the two-stage side utilization
unit (15) is increased in pressure by the booster compressor (46)
by the time that it reaches the outlet port of the two-stage side
circuit (47), thereby making it possible for both the refrigerant
evaporative pressure and the refrigerant evaporative temperature in
the two-stage side utilization unit (15) to be set at lower values
than the single-stage side utilization units (12, 13, 14).
[0025] In the eighth aspect of the present invention, the two-stage
side circuit (47) to which is connected the booster compressor (46)
is connected at the most upstream side in the return-side
interconnecting piping line (19). The refrigerant pressure loss
caused by the return-side interconnecting piping line (19) between
the two-stage side circuit (47) and the heat source unit (11)
exceeds the refrigerant pressure loss caused by the return-side
interconnecting piping line (19) between each of the single-stage
side utilization units (12, 13, 14) and the heat source unit (11).
However, in the two-stage side circuit (47), refrigerant evaporated
in the two-stage side utilization unit (15) is fed out after being
compressed in the booster compressor (46). Consequently, the
refrigerant evaporative temperature in the two-stage side
utilization unit (15) becomes lower than the refrigerant
evaporative temperature in the single-stage side utilization units
(12, 13, 14).
[0026] In the ninth aspect of the present invention, the two-stage
side circuit (47) to which the two-stage side utilization unit (15)
is connected is connected at the most upstream side in the
supply-side interconnecting piping line (18) so that refrigerant
easily flows into the two-stage side utilization unit (15). This
arrangement therefore enables liquid refrigerant to easily flow
into the two-stage side utilization unit (15) capable of being set
at lower values in refrigerant evaporative pressure as well as in
refrigerant evaporative temperature than the single-stage side
utilization units (12, 13, 14).
ADVANTAGEOUS EFFECTS OF THE INVENTION
[0027] In accordance with the first aspect of the present
invention, it is arranged such that the refrigerant evaporative
temperature in the single-stage side utilization unit (14) of
lowest compartment preset temperature is the lowest among the
single-stage side utilization units (12, 13, 14). Consequently, the
refrigerant evaporative temperature in the cooling heat exchanger
(41) of the single-stage side utilization unit (14) of lowest
compartment preset temperature can be set to be the lowest so that
it becomes appropriate with respect to the compartment preset
temperature, whereby compartment cooling by the single-stage side
utilization unit (14) is efficiently performed.
[0028] In accordance with the second aspect of the present
invention, it is arranged such that the refrigerant evaporative
temperature in the single-stage side utilization units (12, 13, 14)
decreases in ascending order of the compartment preset temperature.
This arrangement therefore makes it possible to set the refrigerant
evaporative temperature in the cooling heat exchangers (21, 31, 41)
of the single-stage side utilization units (12, 13, 14) to decrease
in ascending order of the compartment preset temperature so that it
becomes appropriate with respect to the compartment preset
temperature, whereby compartment cooling by the single-stage side
utilization units (12, 13, 14) is efficiently performed.
[0029] In accordance with the third aspect of the present
invention, the length of the return-side interconnecting piping
lines respectively extending from the outlet ports (24, 34, 44) of
the single-stage side utilization units (12, 13, 14) to the inlet
port (61) of the heat source unit (11) is specified, whereby the
refrigerant pressure loss which is caused in the return-side
interconnecting piping line (19) composed of the return-side
interconnecting piping lines respectively extending from the outlet
ports (24, 34, 44) of the single-stage side utilization units (12,
13, 14) to the inlet port (61) of the heat source unit (11) is
easily minimized in one of the return-side interconnecting piping
lines that is connected to the lowest of the single-stage side
utilization units (12, 13, 14) in compartment preset temperature.
This is therefore advantageous for the single-stage side
utilization unit (14) of lowest compartment preset temperature to
efficiently perform its compartment cooling.
[0030] In accordance with the fourth aspect of the present
invention, the length of the return-side interconnecting piping
lines respectively extending from the outlet ports (24, 34, 44) of
the single-stage side utilization units (12, 13, 14) to the inlet
port (61) of the heat source unit (11) is specified, whereby the
refrigerant pressure loss which is caused in the return-side
interconnecting piping line (19) composed of the return-side
interconnecting piping lines respectively extending from the outlet
ports (24, 34, 44) of the single-stage side utilization units (12,
13, 14) to the inlet port (61) of the heat source unit (11) is
easily made to become smaller as the compartment preset temperature
in the single-stage side utilization units (12, 13, 14) connected
by the return-side interconnecting piping lines to the inlet port
(61) of the heat source unit (11) decreases. This is therefore
advantageous for the single-stage side utilization units (12, 13,
14) to efficiently perform their compartment cooling.
[0031] In accordance with the sixth aspect of the present
invention, the single-stage side utilization unit (14) of lowest
compartment preset temperature which requires higher cooling
capability than the single-stage side utilization units (12, 13) is
connected in the return-side interconnecting piping line (19) such
that refrigerant is easily returned to the heat source unit (11)
while the single-stage side utilization unit (14) is connected in
the supply-side interconnecting piping line (18) such that
refrigerant easily flows into the single-stage side utilization
unit (14) from the heat source unit (11), whereby more liquid
refrigerant tends to flow into the single-stage side utilization
unit (14) as compared to the single-stage side utilization units
(12, 13). This therefore makes it possible for the single-stage
side utilization unit (14) of lowest compartment temperature to
exert cooling capability sufficient enough to keep the compartment
at a predetermined preset temperature.
[0032] In accordance with the seventh aspect of the present
invention, even when both the refrigerant evaporative pressure and
the refrigerant evaporative temperature in the two-stage side
utilization unit (15) are set at lower values than the single-stage
side utilization units (12, 13, 14), the refrigerant from the
two-stage side utilization unit (15) is compressed by the booster
compressor (46) to a higher pressure before reaching the outlet
port of the two-stage side circuit (47). Therefore, without
affecting the refrigerant evaporative temperature/pressure in the
single-stage side utilization units (12, 13, 14), the two-stage
side utilization unit (15) is able to exert higher cooling
capability as compared to the single-stage side utilization units
(12, 13, 14).
[0033] In accordance with the ninth aspect of the present
invention, the two-stage side utilization unit (15) capable of
being set at lower values in refrigerant evaporative pressure as
well as in refrigerant evaporative temperature than the
single-stage side utilization units (12, 13, 14) is connected in
the supply-side interconnecting piping line (18) such that
refrigerant easily flows thereinto. Accordingly, more liquid
refrigerant tends to flow into the two-stage side utilization unit
(15), so that even when its compartment preset temperature is set
at a lower value than that of the single-stage side utilization
units (12, 13, 14) the two-stage side utilization unit (15) is able
to exert cooling capability sufficient enough to keep the
compartment at a predetermined preset temperature.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] In the accompanying drawings:
[0035] FIG. 1 is a schematic block diagram of a refrigerating
apparatus according to a first embodiment of the present
invention;
[0036] FIG. 2 is a schematic block diagram of a refrigerating
apparatus according to a second variation of the first embodiment
of the present invention; and
[0037] FIG. 3 is a schematic block diagram of a refrigerating
apparatus according to a second embodiment of the present
invention.
REFERENCE NUMERALS IN THE DRAWINGS
[0038] 11: Outdoor Unit (Heat Source Unit) [0039] 12: First Cold
Storage Showcase (Single-Stage Side Utilization Unit) [0040] 13:
Second Cold Storage Showcase (Single-Stage Side Utilization Unit)
[0041] 14: Third Cold Storage Showcase (Single-Stage Side
Utilization Unit of Lowest Compartment Preset Temperature) [0042]
15: Freeze Storage Showcase (Two-Stage Side Utilization Unit)
[0043] 18: Liquid-Side Interconnecting Piping Line (Supply-Side
Interconnecting Piping Line) [0044] 19: Gas-Side Interconnecting
Pipine Line (Return-Side Interconnecting Piping Line) [0045] 20:
Refrigerant Circuit [0046] 21: Cold Storage Heat Exchanger (Cooling
Heat Exchanger) of First Cold Storage Showcase [0047] 23: Inlet
Port of First Cold Storage Showcase (Inlet Port of Single-Stage
Side Utilization Unit) [0048] 24: Outlet Port of First Cold Storage
Showcase (Outlet Port of Single-Stage Side Utilization Unit) [0049]
29: Compressor [0050] 30: Refrigerating Apparatus [0051] 31: Cold
Storage Heat Exchanger (Cooling Heat Exchanger) of Second Cold
Storage Showcase [0052] 33: Inlet Port of Second Cold Storage
Showcase (Inlet Port of Single-Stage Side Utilization Unit) [0053]
34: Outlet Port of Second Cold Storage Showcase (Outlet Port of
Single-Stage Side Utilization Unit) [0054] 41: Cold Storage Heat
Exchanger (Cooling Heat Exchanger) of Third Cold Storage Showcase
[0055] 43: Inlet Port of Third Cold Storage Showcase (Inlet Port of
Single-Stage Side Utilization Unit) [0056] 44: Outlet Port of Third
Cold Storage Showcase (Outlet Port of Single-Stage Side Utilization
Unit) [0057] 46: Booster Compressor [0058] 47: Two-Stage Side
Circuit [0059] 51: Freeze Storage Heat Exchanger (Cooling Heat
Exchanger) [0060] 53: Inlet Port of Two-Stage Side Circuit [0061]
54: Outlet Port of Two-Stage Side Circuit [0062] 61: Inlet Port of
Outdoor Unit (Inlet Port of Heat Source Unit) [0063] 71: Outlet
Port of Outdoor Unit (Outlet Port of Heat Source Unit)
BEST EMBODIMENT MODE FOR CARRYING OUT THE INVENTION
[0064] In the following, preferred embodiments of the present
invention will be described in detail with reference to the
accompanying drawings.
First Embodiment of the Invention
[0065] The present embodiment provides a refrigerating apparatus
(30). The refrigerating apparatus (30) is installed in, for
example, a convenience store and provides cooling of showcases.
[0066] As shown in FIG. 1, the refrigerating apparatus (30) of the
present embodiment has an outdoor unit (11) serving as a heat
source unit, four showcases (12, 13, 14, 15), and a booster unit
(16). Of these four showcases (12, 13, 14, 15), the showcases (12,
13, 14) are, respectively, first to third cold storage showcases
(12, 13, 14) and the showcase (15) is a freeze storage showcase
(15). The outdoor unit (11) is installed outdoors. On the other
hand, the four showcases (12, 13, 14, 15) are all installed indoors
(for example, in the inside of a convenience store).
[0067] The four showcases (12, 13, 14, 15) are preset at respective
compartment temperatures. More specifically, the preset temperature
of the first cold storage showcase (12) is 10 degrees Centigrade;
the preset temperature of the second cold storage showcase (13) is
5 degrees Centigrade; the preset temperature of the third cold
storage showcase (14) is 2 degrees Centigrade; and the freeze
storage showcase (15) is minus 20 degrees Centigrade.
[0068] The outdoor unit (11) has an outdoor circuit (28). The first
cold storage showcase (12) has a first cold storage circuit (25).
The second cold storage showcase (13) has a second cold storage
circuit (35). The third cold storage showcase (14) has a third cold
storage circuit (45). The freeze storage showcase (15) has a freeze
storage circuit (55). The booster unit (16) has a booster circuit
(65).
[0069] The booster circuit (65) includes a booster compressor (46).
The freeze storage circuit (55) and the booster circuit (65) are
connected together in series. A piping line extending from an inlet
port (53) of the freeze storage circuit (55) to an outlet port (54)
of the booster circuit (65) constitutes a two-stage side circuit
(47).
[0070] In the refrigerating apparatus (30), the cold storage
circuits (25, 35, 45) and the two-stage side circuit (47) are
connected by a liquid-side interconnecting piping line (18) and a
gas-side interconnecting piping line (19) in parallel with each
other with respect to the outdoor circuit (28), thereby
constituting a refrigerant circuit (20). The cold storage showcases
(12, 13, 14) constitute respective single-stage side utilization
units while on the other hand the freeze storage showcase (15)
constitutes a two-stage side utilization unit.
[0071] The outdoor circuit (28) includes a compressor (29) and an
outdoor heat exchanger (17). The compressor (29) is a hermetical,
high pressure dome type scroll compressor. The compressor (29)
compresses refrigerant drawn therein and discharges it. The outdoor
heat exchanger (17) is a fin and tube heat exchanger of the cross
fin type and constitutes a heat source-side heat exchanger. Heat
transfer between refrigerant and outdoor air is effected in the
outdoor heat exchanger (17). In the outdoor unit (11), the pressure
of refrigerant at the inlet port of the compressor (29) is
approximately equal to the pressure of refrigerant at an inlet port
(61) of the outdoor unit (11), and the pressure of refrigerant at
the outlet port of the outdoor heat exchanger (17) is approximately
equal to the pressure of refrigerant at an outlet port (71) of the
outdoor unit (11).
[0072] In each cold storage circuit (25, 35, 45), a cold storage
expansion valve (22, 32, 42) and a cold storage heat exchanger (21,
31, 41) are disposed in the order from the liquid-side end towards
the gas-side end thereof. Each cold storage heat exchanger (21, 31,
41) is a fin and tube heat exchanger of the cross fin type,
constitutes a cooling heat exchanger, and provides cooling of its
associated compartment so that the associated compartment is held
at a predetermined preset temperature. In the cold storage heat
exchangers (21, 31, 41), heat transfer between refrigerant and
compartment air is effected. The cold storage expansion valves (22,
32, 42) are formed by electronic expansion valves.
[0073] In the first cold storage showcase (12), the pressure of
refrigerant at the inlet port of the cold storage expansion valve
(22) is approximately equal to the pressure of refrigerant at an
inlet port (23) of the first cold storage showcase (12), and the
pressure of refrigerant at the outlet port of the cold storage heat
exchanger (21) is approximately equal to the pressure of
refrigerant at an outlet port (24) of the first cold storage
showcase (12). In addition, in the second cold storage showcase
(13), the pressure of refrigerant at the inlet port of the cold
storage expansion valve (32) is approximately equal to the pressure
of refrigerant at an inlet port (33) of the second cold storage
showcase (13), and the pressure of refrigerant at the outlet port
of the cold storage heat exchanger (31) is approximately equal to
the pressure of refrigerant at an outlet port (34) of the second
cold storage showcase (13). In addition, in the third cold storage
showcase (14), the pressure of refrigerant at the inlet port of the
cold storage expansion valve (42) is approximately equal to the
pressure of refrigerant at an inlet port (43) of the third cold
storage showcase (14), and the pressure of refrigerant at the
outlet port of the cold storage heat exchanger (41) is
approximately equal to the pressure of refrigerant at an outlet
port (44) of the third cold storage showcase (14).
[0074] In the freeze storage circuit (55), a freeze storage
expansion valve (52) and a freeze storage heat exchanger (51) are
disposed in the order from the liquid-side end towards the gas-side
end thereof. The freeze storage heat exchanger (51) is a fin and
tube heat exchanger of the cross fin type, constitutes a cooling
heat exchanger, and provides cooling of its associated compartment
so that the associated compartment is held at a predetermined
preset temperature. In the freeze storage heat exchanger (51), heat
transfer between refrigerant and compartment air is effected. The
freeze storage expansion valve (52) is formed by an electronic
expansion valve.
[0075] The booster compressor (46) of the booster unit (16) is a
hermetical, high-pressure dome type scroll compressor and is
connected, at its inlet port, to the outlet port of the freeze
storage heat exchanger (51) of the freeze storage circuit (55). The
booster compressor (46) compresses refrigerant drawn therein from
the freeze storage heat exchanger (51) and then discharges it.
[0076] In the two-stage side circuit (47) extending from the inlet
port (53) of the freeze storage showcase (15) to the outlet port
(54) of the booster unit (16), the pressure of refrigerant at the
inlet port of the freeze storage expansion valve (52) is
approximately equal to the pressure of refrigerant at the inlet
port (53) of the two-stage side circuit (47), and the pressure of
refrigerant at the discharge outlet port of the booster compressor
(46) is approximately equal to the pressure of refrigerant at the
outlet port (54) of the two-stage side circuit (47).
[0077] The liquid-side interconnecting piping line (18) is provided
with three flow branching points (72, 73, 74) at each of which an
interconnecting piping line diverges into two branch
interconnecting piping lines. The branch interconnecting piping
lines are connected, respectively, to the inlet ports (23, 33, 43)
of the cold storage showcases (12, 13, 14) and the inlet port (53)
of the two-stage side circuit (47). Of the three flow branching
points (72, 73, 74), the nearest to the outdoor unit (11) is the
first flow branching point (72); the second nearest to the outdoor
unit (11) is the second flow branching point (73); and the third
nearest to the outdoor unit (11) is the third flow branching point
(74).
[0078] The liquid-side interconnecting piping line (18) is made up
of: a main piping line (1) extending from the outlet port (71) of
the outdoor unit (11) to the first flow branching point (72); a
first connecting piping line (2a) extending from the first flow
branching point (72) to the second flow branching point (73); a
second connecting piping line (2b) extending from the second flow
branching point (73) to the third flow branching point (74); a
first branch piping line (3a) extending from the first flow
branching point (72) to the inlet port (53) of the two-stage side
circuit (47); a second branch piping line (3b) extending from the
second flow branching point (73) to the inlet port (43) of the
third cold storage showcase (14); a third branch piping line (3c)
extending from the third flow branching point (74) to the inlet
port (33) of the second cold storage showcase (13); and a fourth
branch piping line (3d) extending from the third flow branching
point (74) to the inlet port (23) of the first cold storage
showcase (12). In other words, in the liquid-side interconnecting
piping line (18) which is a supply-side interconnecting piping line
extending from the outlet port (71) of the outdoor unit (11), the
two-stage side circuit (47) is connected at the most upstream side,
and the lowest of the three cold storage showcases (12, 13, 14) in
compartment preset temperature, i.e., the third cold storage
showcase (14), is connected at the most upstream side
thereamong.
[0079] The gas-side interconnecting piping line (19) is provided
with three flow merging points (65, 66, 67) at each of which, two
interconnecting piping lines join together. The merged
interconnecting piping lines are connected, respectively, to the
outlet ports (24, 34, 44) of the cold storage showcases (12, 13,
14) and the outlet port (54) of the two-stage side circuit (47). Of
the three flow merging points (65, 66, 67), the nearest to the
outdoor unit (11) is the first flow merging point (65); the second
nearest to the outdoor unit (11) is the second flow merging point
(66); and the third nearest to the outdoor unit (11) is the third
flow merging point (67).
[0080] The gas-side interconnecting piping line (19) is made up of:
a main piping line (4) extending from the first flow merging point
(65) to the inlet port (61) of the outdoor unit (11); a third
connecting piping line (5a) extending from the first flow merging
point (65) to the second flow merging point (66); a fourth
connecting piping line (5b) extending from the second flow merging
point (66) to the third flow merging point (67); a first flow
merging piping line (6a) extending from the outlet port (54) of the
two-stage side circuit (47) to the third flow merging point (67); a
second flow merging piping line (6b) extending from the outlet port
(44) of the third cold storage showcase (14) to the first flow
merging point (65); a third flow merging piping line (6c) extending
from the outlet port (34) of the second cold storage showcase (13)
to the second flow merging point (66); and a fourth flow merging
piping line (6d) extending from the outlet port (24) of the first
cold storage showcase (12) to the third flow merging point (67). In
other words, in the gas-side interconnecting piping line (19) which
is a return-side interconnecting piping line extending to the inlet
port (61) of the outdoor unit (11), the two-stage side circuit (47)
is connected at the most upstream side, and the lowest of the three
cold storage showcases (12, 13, 14) in compartment preset
temperature, i.e., the third cold storage showcase (14), is
connected at the most downstream side thereamong.
[0081] Here, let L1 be the length of an interconnecting piping line
extending from the outlet port (24) of the first cold storage
showcase (12) to the inlet port (61) of the outdoor unit (11). The
length (L1 is the sum of the length of the main piping line (4),
the length of the third connecting piping line (5a), the length of
the fourth connecting piping line (5b), and the length of the
fourth flow merging piping line (6d). Let L2 be the length of an
interconnecting piping line extending from the outlet port (34) of
the second cold storage showcase (13) to the inlet port (61) of the
outdoor unit (11). The length (L2) is the sum of the length of the
main piping line (4), the length of the third connecting piping
line (5a), and the length of the third flow merging piping line
(6c). Let L3 bet the length of an interconnecting piping line
extending from the outlet port (44) of the third cold storage
showcase (14) to the inlet port (61) of the outdoor unit (11). The
length (L3) is the sum of the length of the main piping line (4)
and the length of the second flow merging piping line (6b). Let L4
be the length of an interconnecting piping line extending from the
outlet port (54) of the two-stage side circuit (47) to the inlet
port (61) of the outdoor unit (11). The length (L4) is the sum of
the length of the main piping line (4), the length of the third
connecting piping line (5a), the length of the fourth connecting
piping line (5b), and the length of the first flow merging piping
line (6a).
[0082] The relationship between the lengths of the interconnecting
piping lines respectively extending from the outlet ports (24, 34,
44, 54) of the cold storage showcases (12, 13, 14) and the
two-stage side circuit (47) to the inlet port (61) of the outdoor
unit (11) is: L3<L2<L1<L4. Stated another way, the length
of the interconnecting piping lines extending from the outlet ports
(24, 34, 44) of the cold storage showcases (12, 13, 14) to the
inlet port (61) of the outdoor unit (11) is set to become shorter
in ascending order of the compartment preset temperature of the
cold storage showcases (12, 13, 14). In addition, the length of the
interconnecting piping line extending from the outlet port (54) of
the two-stage side circuit (47) to the inlet port (61) of the
outdoor unit (11) is longer than any one of the interconnecting
piping lines respectively extending from the outlet ports (24, 34,
44) of the cold storage showcases (12, 13, 14) to the inlet port
(61) of the outdoor unit (11).
[0083] In the refrigerant circuit (20), the pipe diameter of each
of the sections (4, 5, 6) in the gas-side (return side)
interconnecting piping line (19) is determined depending on the
refrigerant flow rate in each section (4, 5, 6). Consequently, the
loss of refrigerant pressure caused by the gas-side (return side)
interconnecting piping line (19) becomes approximately equal in
value per unit length in any one of the interconnecting piping
lines. As a result, the loss of refrigerant pressure caused by the
return-side interconnecting piping lines respectively extending
from the outlet ports (24, 34, 44) of the cold storage showcases
(12, 13, 14) to the inlet port (61) of the outdoor unit (11)
decreases as the length of the interconnecting piping lines
decreases, and as the preset temperature of the cold storage
showcases (12, 13, 14) decreases. In addition, the loss of
refrigerant pressure caused by the interconnecting piping line
extending from the outlet port (54) of the two-stage side circuit
(47) to the inlet port (61) of the outdoor unit (11) is greater
than the refrigerant pressure loss caused by any one of the
interconnecting piping lines respectively extending from the outlet
ports (24, 34, 44) of the cold storage showcases (12, 13, 14) to
the inlet port (61) of the outdoor unit (11).
Running Operation
[0084] Description will be made in regard to the operation of the
refrigerating apparatus (30) of the present embodiment. In the
refrigerating apparatus (30), refrigerant is circulated between the
outdoor unit (11) and each of the cold storage showcase (12, 13,
14), and single-stage compression refrigeration cycles are
performed in which the cooling heat exchangers (21, 31, 41) of the
cold storage showcases (12, 13, 14) function as evaporators.
Further, refrigerant is circulated between the outdoor unit (11)
and the two-stage side circuit (47), and two-stage compression
refrigeration cycles are performed in which the cooling heat
exchanger (51) of the freeze storage showcase (15) functions as an
evaporator.
[0085] When the compressor (29) of the outdoor unit (11) is
operated, refrigerant is compressed in the compressor (29), passes
through the outdoor circuit (28), and flows into the outdoor heat
exchanger (17). In the outdoor heat exchanger (17), the refrigerant
dissipates heat to outdoor air and becomes condensed. The
refrigerant condensed in the outdoor heat exchanger (17) exits the
outdoor unit (11) and flows into the main piping line (1)
constituting a part of the liquid-side interconnecting piping line
(18). And the refrigerant which has flowed into the main piping
line (1) enters the cold storage circuits (25, 35, 45) and the
freeze storage circuit (55) from the flow branching points (72, 73,
74).
[0086] The refrigerant which has entered each cold storage showcase
(25, 35, 45) is reduced in pressure in each cold storage expansion
valve (22, 32, 42) and is then introduced into each cold storage
heat exchanger (21, 31, 41). In each cold storage heat exchanger
(21, 31, 41), the refrigerant absorbs heat from compartment air and
becomes evaporated. In the first cold storage showcase (12),
compartment air cooled in the cold storage heat exchanger (21) is
supplied into its associated compartment, whereby the associated
compartment temperature is held at approximately a preset
temperature (10 degrees Centigrade). In the second cold storage
showcase (13), compartment air cooled in the cold storage heat
exchanger (31) is supplied into its associated compartment, whereby
the associated compartment temperature is held at approximately a
preset temperature (5 degrees Centigrade). In the third cold
storage showcase (14), compartment air cooled in the cold storage
heat exchanger (41) is supplied into its associated compartment,
whereby the associated compartment temperature is held at
approximately a preset temperature (2 degrees Centigrade). The
refrigerant evaporated in the cold storage heat exchangers (21, 31,
41) flows into the second to fourth flow merging piping lines (6b,
6c, 6d).
[0087] Meanwhile, the refrigerant which has flowed into the freeze
storage circuit (55) is reduced in pressure in the freeze storage
expansion mechanism (52) and is then introduced into the freeze
storage heat exchanger (51). In the freeze storage heat exchanger
(51), the refrigerant absorbs heat from compartment air and becomes
evaporated. In the freeze storage showcase (15), compartment air
cooled in the freeze storage heat exchanger (51) is supplied into
its associated compartment, whereby the compartment temperature is
held at approximately a preset temperature (minus 20 degrees
Centigrade). The refrigerant evaporated in the freeze storage heat
exchanger (51) flows through the freeze storage circuit (55) into
the booster circuit (65). The refrigerant which has flowed into the
booster circuit (65) is drawn into the booster compressor (46) and
discharged after being compressed by the booster compressor (46).
The refrigerant discharged out of the booster compressor (46) flows
into the first flow merging piping line (6a).
[0088] The loss of refrigerant pressure caused by the return-side
interconnecting piping line (19) composed of the return-side
interconnecting piping lines respectively extending from the outlet
ports (24, 34, 44) of the cold storage showcases (12, 13, 14) to
the inlet port (61) of the outdoor unit (11) is set such that the
lowest valued refrigerant pressure loss is caused by a return-side
interconnecting piping line of the return-side interconnecting
piping line (19) that extends from the third cold storage showcase
(14). Accordingly, the refrigerant evaporative temperature in each
of the cold storage showcases (12, 13, 14) is set as follows. That
is, the refrigerant evaporative temperature in the third cold
storage showcase (14) is the lowest; the refrigerant evaporative
temperature in the second cold storage showcase (13) is the second
lowest; and the refrigerant evaporative temperature in the first
cold storage showcase (12) is the third lowest, so that the cold
storage showcases (12, 13, 14) are maintained at their respective
compartment preset temperatures.
[0089] In addition, the refrigerant evaporative temperature in the
freeze storage showcase (15) is set lower than any of the cold
storage showcases (12, 13, 14). However, before its arrival at the
outlet port of the two-stage side circuit (47), the refrigerant
from the freeze storage showcase (15) is compressed in the booster
compressor (46) and, as a result, its pressure is increased.
Therefore, it becomes possible to provide compartment cooling in
the freeze storage showcase (15) at high cooling capability,
without affecting the evaporative temperature and pressure in the
cold storage showcases (12, 13, 14).
[0090] Refrigerant which has entered each flow merging piping line
(6a, 6d, 6c, 6d) merges at each flow merging point (65, 66, 67) and
flows through the main piping line (4) into the outdoor circuit
(28). The refrigerant which has entered the outdoor circuit (28) is
drawn into the compressor (29), compressed by the compressor (29),
and discharged out of the compressor (29). In the refrigerant
circuit (20), such a refrigerant circulation cycle is repeatedly
carried out.
Advantageous Effects of the First Embodiment
[0091] In the first embodiment, the loss of refrigerant pressure
caused by the return-side interconnecting piping line (19) composed
of the return-side interconnecting piping lines respectively
extending from the outlet ports (24, 34, 44) of the cold storage
showcase (12, 13, 14) to the inlet port (61) of the outdoor unit
(11) decreases as the compartment preset temperature of the cold
storage showcases (12, 13, 14) decreases. Consequently, in order
that the refrigerant evaporative temperature in the cooling heat
exchangers (21, 31, 41) of the cold storage showcases (12, 13, 14)
may become adequate with respect to the compartment preset
temperature, the refrigerant evaporative temperature is set lower
in ascending order of the compartment preset temperature. This
therefore enables each of the cold storage showcases (12, 13, 14)
to efficiently provide compartment cooling.
[0092] In addition, in the first embodiment, the third cold storage
showcase (14) of lowest compartment preset temperature which
requires higher cooling capability in comparison with the first and
second cold storage showcases (12, 13) is connected in the gas-side
(return-side) interconnecting piping line (19) such that
refrigerant easily returns to the outdoor unit (11) from the third
cold storage showcase (14) while on the other hand the third cold
storage showcase (14) is connected in the liquid-side (supply side)
interconnecting piping line (18) such that refrigerant easily flows
into the third cold storage showcase (14) from the outdoor unit
(11), whereby, when compared to the first and second cold storage
showcases (12, 13), more refrigerant easily flows through the third
cold storage showcase (14). Accordingly, the third cold storage
showcase (14) is able to exert cooling capability sufficient enough
to maintain its associated compartment at a predetermined preset
temperature.
[0093] In addition, in the first embodiment, even when both the
evaporative pressure and the evaporative temperature of refrigerant
in the freeze storage showcase (15) are set at lower values than
the cold storage showcases (12, 13, 14), the refrigerant from the
freeze storage showcase (15) is compressed in the booster
compressor (46) before its arrival at the outlet port of the
two-stage side circuit (47), whereby the refrigerant is increased
in pressure. This therefore makes it possible to enable the freeze
storage showcase (15) to exert higher cooling capability than the
cold storage showcases (12, 13, 14), without affecting the
refrigerant evaporating pressure/temperature in the cold storage
showcases (12, 13, 14).
[0094] In addition, in the first embodiment, the freeze storage
showcase (15) whose refrigerant evaporative pressure and
temperature are set at lower values than the cold storage showcases
(12, 13, 14) is connected in the liquid-side (supply-side)
interconnecting piping line (18) such that refrigerant easily flows
into the freeze storage showcase (15). Accordingly, since much
liquid refrigerant easily flows into the freeze storage showcase
(15), this makes it possible for the freeze storage showcase (15)
to exert cooling capability sufficient enough to maintain the
associated compartment at a predetermined preset temperature.
First Variation of the First Embodiment
[0095] Description will be made in regard to a first variation of
the first embodiment. The first variation differs from the first
embodiment in that the first and second cold storage showcases (12,
13) are modified in their compartment preset temperature and the
fourth connecting piping line (5b) and the fourth flow merging
piping line (6d) are modified in their thickness (inside
diameter).
[0096] In the first variation, the compartment preset temperature
of the first cold storage showcase (12) is 5 degrees Centigrade and
the compartment preset temperature of the second cold storage
showcase (13) is 10 degrees Centigrade. In addition, the thickness
of the fourth connecting piping line (5b) and the thickness of the
fourth flow merging piping line (6d) are determined so that the sum
of the refrigerant pressure loss caused by the fourth connecting
piping line (5b) and the refrigerant pressure loss caused by the
fourth flow merging piping line (6d) falls below the refrigerant
pressure loss caused by the third flow merging piping line (6c).
Because of such arrangement, the refrigerant pressure loss caused
by the interconnecting piping line extending from the outlet port
(24) of the first cold storage showcase (12) to the inlet port (61)
of the outdoor unit (11) is smaller than the refrigerant pressure
loss caused by the interconnecting piping line extending from the
outlet port (34) of the second cold storage showcase (13) to the
inlet port (61) of the outdoor unit (11). As a result, the loss of
refrigerant pressure which is caused in the return-side
interconnecting piping line (19) composed of the return-side
interconnecting piping lines respectively extending from the outlet
ports (24, 34, 44) of the cold storage showcases (12, 13, 14) to
the inlet port (61) of the outdoor unit (11) decreases as the
compartment preset temperature of the cold storage showcases (12,
13, 14) decreases, as in the first embodiment.
[0097] In accordance with the first variation, the length of the
return-side interconnecting piping lines respectively extending
from the outlet ports (24, 34, 44) of the cold storage showcases
(12, 13, 14) to the inlet port (61) of the outdoor unit does not
decrease in ascending order of the compartment preset temperature
of the cold storage showcases (12, 13, 14). However, by adjusting
the thickness of the interconnecting piping lines, the refrigerant
pressure loss caused by the interconnecting piping lines
respectively extending from the outlet ports (24, 34, 44) of the
cold storage showcase s(12, 13, 14) is made to decrease in
ascending order of the compartment preset temperature of the cold
storage showcases (12, 13, 14). Accordingly, regardless of the
layout of the outdoor unit (11) and the layout of the cold storage
showcases (12, 13, 14), if the refrigerant pressure loss which is
caused in the interconnecting piping lines respectively extending
from the outlet ports (24, 34, 44) of the cold storage showcases
(12, 13, 14) to the inlet port (61) of the outdoor unit (11) is
controlled, the evaporative temperature of refrigerant in the
cooling heat exchangers (21, 31, 41) of the cold storage showcases
(12, 13, 14) is lowered in ascending order of the compartment
preset temperature so that the refrigerant evaporative temperature
becomes adequate with respect to the compartment preset
temperature, thereby enabling the cold storage showcases (12, 13,
14) to efficiently provide compartment cooling.
Second Variation of the First Embodiment
[0098] Description will be made in regard to a second variation of
the first embodiment. Referring to FIG. 2, there is shown a
schematic arrangement of a refrigerating apparatus (30) according
to the second variation. Unlike the first embodiment, the
refrigerating apparatus (30) of the second variation is provided
with neither the freeze storage showcase (15) nor the booster unit
(16).
[0099] More specifically, the refrigerating apparatus (30) of the
second variation has an outdoor unit (11) and three cold storage
showcases (12, 13, 14). And, as in the first embodiment, in the
liquid-side interconnecting piping line (18) which is a supply-side
interconnecting piping line extending from the outlet port (71) of
the outdoor unit (11), the lowest of the three cold storage
showcases (12, 13, 14) in compartment preset temperature, i.e., the
third cold storage showcase (14), is connected at the most upstream
side. In addition, in the gas-side interconnecting piping line (19)
which is a return-side interconnecting piping line extending
towards the inlet port (61) of the outdoor unit (11), the lowest of
the three cold storage showcases (12, 13, 14) in compartment preset
temperature, i.e., the third cold storage showcase (14), is
connected at the most downstream side.
Second Embodiment of the Present Invention
[0100] Referring now to FIG. 3, there is shown a refrigerating
apparatus (30) according to a second embodiment of the present
invention. Unlike the first embodiment, in the refrigerating
apparatus (30) of the second embodiment, the two-stage side circuit
(47) is connected at the most downstream side in the gas-side
(return-side) interconnecting piping line (19). Hereinafter, the
difference of the second embodiment from the first embodiment will
be described more specifically.
[0101] The gas-side interconnecting piping line (19) is composed
of: a main piping line (4) extending from the first flow merging
point (65) to the inlet port (61) of the outdoor unit (11); a third
connecting piping line (5a) extending from the first flow merging
point (65) to the second flow merging point (66); a fourth
connecting piping line (5b) extending from the second flow merging
point (66) to the third flow merging point (67); a first flow
merging piping line (6a) extending from the outlet port (54) of the
two-stage side circuit (47) to the first flow merging point (65); a
second flow merging piping line (6b) extending from the outlet port
(44) of the third cold storage showcase (14) to the second flow
merging point (66); a third flow merging piping line (6c) extending
from the outlet port (34) of the second cold storage showcase (13)
to the third flow merging point (67); and a fourth flow merging
piping line (6d) extending from the outlet port (24) of the first
cold storage showcase (12) to the third flow merging point (67). In
other words, in the gas-side interconnecting piping line (19) which
is a return-side interconnecting piping line extending to the inlet
port (61) of the outdoor unit (11), the two-stage side circuit (47)
is connected at the most downstream side, and the lowest of the
three cold storage showcases (12, 13, 14) in compartment preset
temperature, i.e., the third cold storage showcase (14), is
connected at the most downstream side among the three cold storage
showcases (12, 13, 14).
[0102] The length of the interconnecting piping lines respectively
extending from the outlet ports (24, 34, 44) of the cold storage
showcases (12, 13, 14) becomes shorter as the compartment preset
temperature of the cold storage showcases (12, 13, 14) becomes
lower. In addition, the length of the interconnecting piping line
extending from the outlet port (54) of the two-stage side circuit
(47) to the inlet port (61) of the outdoor unit (11) is shorter
than any of the interconnecting piping lines respectively extending
from the outlet ports (24, 34, 44) of the cold storage showcases
(12, 13, 14) to the inlet port (61) of the outdoor unit (11).
[0103] In the refrigerant circuit (20), the pipe diameter of each
of the sections (4, 5, 6) in the gas-side (return-side)
interconnecting piping line (19) is determined depending on the
flow rate of refrigerant in each section. Consequently, the loss of
refrigerant pressure caused by the gas-side (return-side)
interconnecting piping line (19) becomes approximately equal in
value per unit length in any of the interconnecting piping lines.
As a result, the loss of refrigerant pressure caused by the
return-side interconnecting piping lines respectively extending
from the outlet ports (24, 34, 44) of the cold storage showcases
(12, 13, 14) decreases as the length of the interconnecting piping
lines decreases and as the compartment preset temperature of the
cold storage showcases (12, 13, 14) decreases. In addition, the
loss of refrigerant pressure caused by the interconnecting piping
line extending from the outlet port (54) of the two-stage side
circuit (47) to the inlet port (61) of the outdoor unit (11) is
smaller than the loss of refrigerant pressure caused by any of the
interconnecting piping lines extending from the outlet ports (24,
34, 44) of the cold storage showcases (12, 13, 14) to the inlet
port (61) of the outdoor unit (11).
Advantageous Effects of the Second Embodiment
[0104] In the second embodiment, as in the first embodiment, the
loss of refrigerant pressure caused by the return-side
interconnecting piping line (19) composed of the return-side
interconnecting piping lines respectively extending from the outlet
ports (24, 34, 44) of the cold storage showcase (12, 13, 14) to the
inlet port (61) of the outdoor unit (11) decreases as the
compartment preset temperature of the cold storage showcases (12,
13, 14) decreases. Consequently, in order that the refrigerant
evaporative temperature in the cooling heat exchangers (21, 31, 41)
of the cold storage showcases (12, 13, 14) may become adequate with
respect to the compartment preset temperature, the refrigerant
evaporative temperature is set lower in ascending order of the
compartment preset temperature. This therefore enables each of the
cold storage showcases (12, 13, 14) to efficiently provide
compartment cooling.
[0105] In addition, in the second embodiment, the loss of
refrigerant pressure which caused in the return-side
interconnecting piping line (19) composed of the return-side
interconnecting piping lines respectively extending from the outlet
ports (24, 34, 44) of the single-stage side utilization units (12,
13, 14) to the inlet port (61) of the outdoor unit (11) is set such
that the lowest valued refrigerant pressure loss is caused by a
return-side interconnecting piping line of the return-side
interconnecting piping line (19) that is connected to the freeze
storage showcase (15), and among the outlet ports (24, 34, 44) of
the cold storage showcases (12, 13, 14) and the outlet port (54) of
the two-stage side circuit (47), the outlet port (54) of the
two-stage side circuit (47) has the lowest refrigerant pressure.
This therefore makes it possible to suppress and lessen the
refrigerant pressure at the outlet port (54) of the freeze storage
showcase (15), i.e., the discharge pressure of the booster
compressor (46), whereby the difference in pressure between the
inlet and outlet ports of the booster compressor (46) can be
reduced. Accordingly, it becomes possible to suppress and lessen
the amount of power consumption in the booster compressor (46).
Another Embodiment
[0106] With respect to each of the foregoing embodiments, it may be
arranged such that in the liquid-side (supply-side) interconnecting
piping line (18) or in the gas-side (return-side) interconnecting
piping line (19) the freeze storage showcase (15) is disposed
neither at the most upstream side nor at the most downstream side
as in the foregoing embodiments, but between two of the cold
storage showcases (12, 13, 14).
[0107] In addition, with respect to each of the foregoing
embodiments, it may be arranged such that the cold storage
showcases (12, 13, 14) are preset at the same compartment preset
temperature as each other. In such a case, it is preferable that
the return-side interconnecting piping lines respectively extending
from the outlet ports (24, 34, 44) of the cold storage showcases
(12, 13, 14) to the inlet port (61) of the outdoor unit (11) cause
approximately the same refrigerant pressure loss.
[0108] In addition, with respect to each of the foregoing
embodiments, it may be arranged such that the refrigerant circuit
(20) is provided with four or more cold storage showcases, and that
the four or more cold storage showcases are connected in parallel
with the outdoor unit (11).
[0109] In addition, with respect to each of the foregoing
embodiments, it may be arranged such that an air conditioning unit
is provided in the refrigerant circuit (20). In such a case, it is
preferable that the air conditioning unit is connected to the
outdoor unit (11) by an interconnecting piping line other than the
liquid- and gas-side interconnecting piping lines (18, 19).
[0110] It should be noted that the above-descried embodiments are
essentially preferable examples which are not intended in any sense
to limit the scope of the present invention, its application, or
its application range.
INDUSTRIAL APPLICABILITY
[0111] As has been described above, the present invention finds its
utility in the field of refrigerating apparatuses in which a
plurality of utilization units are connected in parallel with a
heat source unit.
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