U.S. patent application number 10/590819 was filed with the patent office on 2008-03-06 for variable capacity modular combined refrigerating installation by frequency conversion.
Invention is credited to Ningfan Zhao.
Application Number | 20080053114 10/590819 |
Document ID | / |
Family ID | 34892090 |
Filed Date | 2008-03-06 |
United States Patent
Application |
20080053114 |
Kind Code |
A1 |
Zhao; Ningfan |
March 6, 2008 |
Variable Capacity Modular Combined Refrigerating Installation by
Frequency Conversion
Abstract
A variable capacity modular combined refrigerating installation,
which has several modular refrigerating units. Each modular unit
has a refrigerating circle, which includes a refrigerating
compressor set (1), an evaporator (4) and a condenser (10). A flow
control valve (6) is mounted at the refrigerating medium
inlet/outlet port of the evaporator (4); and/or a flow control
valve (11) is mounted at the inlet/outlet port of the condenser
(10). The refrigerating compressor set (1) comprises an adjustable
frequency motor (1A) and a compressor (1B) with magnetic suspend
bearings. Each modular unit is also provided with an inlet pressure
sensor (26) and/or discharge pressure sensor (27). The installation
provided with a refrigerating water temperature sensor (19), a
sensor (20) for pressure difference between supply and return at
the installation side and a sensor (21) for pressure difference
between supply and return at the load side; and a sensor (22) for
pressure difference between supply and return at the installation
side. The present invention can decrease the power consumption of
the air conditioning system and provide a convenient and improved
control.
Inventors: |
Zhao; Ningfan; (Guangdong,
CN) |
Correspondence
Address: |
BAKER & HOSTETLER LLP
WASHINGTON SQUARE, SUITE 1100, 1050 CONNECTICUT AVE. N.W.
WASHINGTON
DC
20036-5304
US
|
Family ID: |
34892090 |
Appl. No.: |
10/590819 |
Filed: |
April 14, 2004 |
PCT Filed: |
April 14, 2004 |
PCT NO: |
PCT/CN04/00346 |
371 Date: |
July 20, 2007 |
Current U.S.
Class: |
62/115 ; 165/166;
62/168; 62/228.3 |
Current CPC
Class: |
F25B 2700/1931 20130101;
F25B 2400/13 20130101; F25B 2339/047 20130101; F25B 2700/21171
20130101; Y02B 30/70 20130101; F25B 2700/1933 20130101; F25B 1/04
20130101; F25B 49/02 20130101; F25B 39/022 20130101; F25B 2400/06
20130101; F25B 2600/13 20130101; Y02B 30/745 20130101 |
Class at
Publication: |
62/115 ; 165/166;
62/168; 62/228.3 |
International
Class: |
F25B 1/00 20060101
F25B001/00; F28F 3/00 20060101 F28F003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 25, 2004 |
CN |
CN 200410006016.X |
Claims
1. A variable capacity modular combined refrigerating installation,
which consists of multiple refrigerating modular units, each
modular unit comprising one or more refrigerating cycles which
includes a refrigerating medium and refrigerating compressor set,
an evaporator and a condenser, comprising: a flow control valve for
the refrigerating medium mounted at one of the refrigerating medium
inlet/outlet ports of the evaporator, and a flow control valve of
the refrigerating medium is mounted at least one of the
inlet/outlet ports of the condenser; and a frequency conversion
motor and a compressor with magnetic suspension bearings disposed
as part of the refrigerating compressor set.
2. A modular combined refrigerating installation according to claim
1, further comprising at least one of: a suction pressure sensor
mounted at the suction port of the compressor set to transfer
pressure information for controlling the working capacity of the
compressor set; and a discharge pressure sensor mounted at the
outlet port of the compressor to transfer pressure information for
controlling the opening ratio of said flow control valve of cooling
medium.
3. A modular combined refrigerating installation according to claim
1, further comprising: a temperature sensor to collect and transfer
parameters of the refrigerating water temperature of the
installation for controlling the opening ratio of said flow control
valve of refrigerating medium.
4. A modular combined refrigerating installation according to claim
1, further comprising: a sensor for pressure difference between
supply and return at the installation side and a sensor for
pressure difference between supply and return at the load side in
the refrigerating medium system, to collect and transfer parameters
of the pressure difference between supply and return for
calculating and controlling a working frequency of the delivery
pump.
5. A modular combined refrigerating installation according to claim
1, further comprising: a sensor for pressure difference between
supply and return at the installation side in the cooling medium
system to calculate and control a working frequency of the delivery
pump.
6. A modular combined refrigerating installation according to claim
1, further comprising: a magnetic bearing sensor is mounted at each
magnetic bearing of the compressor.
7. A modular combined refrigerating installation according to claim
1, wherein said evaporator is a plate heat exchanger of full liquid
evaporation type, which has an inner core and an outer shell, said
core is formed by welding a certain number of metal plate of
certain geometric shape according to a predetermined rule; said
outer shell is a barrel shaped container with a circle or square
section; and in said evaporator, there are two or more kinds of
medium flowing channels which are isolated from each other.
8. A modular combined refrigerating installation according to claim
7, wherein each modular unit is provided with an economizer, and
the liquid cryogen from said condenser is divided into two parts,
one part after being throttled super cools the other part, while
said one part absorbs heat and evaporates itself.
9. A modular combined refrigerating installation according to claim
8, wherein a liquid level control throttling expansion device is
mounted between said condenser and the plate heat exchanger of full
liquid evaporation type.
10. A modular combined refrigerating installation according to
claim 9, wherein a gas-liquid separator is mounted between the
suction port of the compressor and the plate heat exchanger of full
liquid evaporation type.
11. A modular combined refrigerating installation according to
claim 1, wherein the general circuit of the modular refrigerating
installation is controlled by a master controller, and the circuit
of each modular unit is controlled by a microprocessor
controller.
12. A modular combined refrigerating installation according to
claim 2, wherein the general circuit of the modular refrigerating
installation is controlled by a master controller, and the circuit
of each modular unit is controlled by a microprocessor
controller.
13. A modular combined refrigerating installation according to
claim 2, further comprising: a temperature sensor to collect and
transfer parameters of the refrigerating water temperature of the
installation for controlling the opening ratio of said flow control
valve of refrigerating medium.
14. A modular combined refrigerating installation according to
claim 2, further comprising: a sensor for pressure difference
between supply and return at the installation side and a sensor for
pressure difference between supply and return at the load side in
the refrigerating medium system, to collect and transfer parameters
of the pressure difference between supply and return for
calculating and controlling a working frequency of the delivery
pump.
15. A modular combined refrigerating installation according to
claim 2, further comprising: a sensor for pressure difference
between supply and return at the installation side in the cooling
medium system to calculate and control a working frequency of the
delivery pump.
16. A modular combined refrigerating installation according to
claim 2, further comprising: a magnetic bearing sensor is mounted
at each magnetic bearing of the compressor.
17. A modular combined refrigerating installation according to
claim 2, wherein said evaporator is a plate heat exchanger of full
liquid evaporation type, which has an inner core and an outer
shell, said core is formed by welding a certain number of metal
plate of certain geometric shape according to a predetermined rule;
said outer shell is a barrel shaped container with a circle or
square section; and in said evaporator, there are two or more kinds
of medium flowing channels which are isolated from each other.
Description
TECHNICAL FIELD
[0001] The present invention relates to a refrigerating
installation, especially to a variable capacity modular combined
refrigerating installation by frequency conversion.
BACKGROUND ART
[0002] The modular combined refrigerating installations have been
widely used for design and application of the refrigerating water
installation of air conditioning system. According to the
requirement of installation load of the building, the modular
combined refrigerating water installation is composed of multiple
standard refrigerating modular units, and the installation capacity
of the system may be increase or decrease at any time, so it can be
used flexibly. Also, because each refrigerating modular unit is a
complete refrigerating system, the number of the running modular
units may be increased or decreased under the control of the master
controller according to the need of the system load. So not only
the outlet of the installation highly correspond with the need of
the system, but also the installation has peak running efficiency
in the low load running state. Thus the running efficiency will not
be decreased due to the decrease of the load, thereby decreasing
the running cost of the installation. Furthermore, the modular
combined refrigerating water installation has highly reliability.
Though some modular units may have failure, other part of the
installation can keep on running, and the wrong part of the
installation can be examined and repaired when the installation is
running. Thus, the modular combined refrigerating installation has
many advantages over other systems. However, it is found through
several years of uses that there is a possibility to decrease the
power consumption and improve the control level besides the
advantages of the modular refrigerating installation.
SUMMARY OF THE INVENTION
[0003] The purpose of the invention is to provide a variable
capacity modular combined refrigerating installation by frequency
conversion. It is improved on the basis of the prior modular
refrigerating installation, to decrease power consumption and
improve control level.
[0004] The purpose of the invention is carried out according to the
following technical solution.
[0005] The variable capacity modular combined refrigerating
installation of the invention is composed of multiple refrigerating
modular units. Each modular unit has one or more refrigerating
cycles, which include a refrigerating compressor set, an evaporator
and a condenser. Wherein:
[0006] A flow control valve is mounted at one of the refrigerating
medium inlet/outlet ports of the evaporator, and at one of the
inlet/outlet ports of the condenser, at least; that is to say, a
flow control valve of the refrigerating medium is mounted at the
inlet/outlet port of the evaporator, a flow control valve of the
cooling medium is mounted at the inlet/outlet port of the
condenser.
[0007] The refrigerating compressor set as used includes an
adjustable frequency motor and a compressor with magnetic
suspension bearings.
[0008] A suction pressure sensor is mounted at the inlet port of
the compressor to transfer the pressure information for controlling
the work capacity of the compressor set; and/or a discharge
pressure sensor is mounted at the outlet port of the compressor to
transfer the pressure information for controlling the opening ratio
of the flow control valve of the cooling medium.
[0009] There is a refrigerating water temperature sensor for
collecting and transferring the temperature parameters of
refrigerating water in the installation to control the opening
ratio of the flow control valve of the refrigerating medium.
[0010] There are a sensor for pressure difference between supply
and return at the installation side and a sensor for pressure
difference between supply and return at the load side in the
refrigerating medium system for collecting and transferring the
parameters of pressure difference between supply and return to
calculate and control the working frequency of the output pump.
[0011] There is a sensor for pressure difference between supply and
return at the installation side and a sensor for pressure
difference between supply and return at the installation side in
the cooling medium system for collecting and transferring the
parameters of the pressure difference between supply and return, to
calculate and control the working frequency of the output pump.
[0012] A magnetic bearing sensor is mounted at each magnetic
bearing of the compressor respectively.
[0013] Said evaporator is a plate heat exchanger of full liquid
evaporation type, which is composed of an inner core and an outer
shell, said core is formed by welding a certain number of metal
plates of certain geometric shape stacked according to a certain
rule; said outer shell is a barrel shaped container with a circle
or square section. There are two or more kinds of medium flowing
channels in said evaporator, which are isolated from each
other.
[0014] There is an economizer in each modular unit. The liquid
cryogen exited from the condenser is divided into two parts, one
part super cools the other part after being throttled and then
evaporates. Since the cryogen after the evaporation has a pressure
higher than the outlet pressure of the cryogen of evaporator, it
enters into the intermediate pressure suction port of the condenser
1B. This economizer cycle can increase the refrigerating capacity
and the refrigerating efficiency of a refrigerating unit.
[0015] A throttling expansion device of liquid level control is
mounted between the condenser and the plate heat exchanger of full
liquid evaporation type.
[0016] A gas-liquid separator is mounted between the suction port
of the compressor and the plate heat exchanger of full liquid
evaporation type.
[0017] The general circuit of the modular combined refrigerating
installation is controlled by a master controller, and the circuit
of each modular unit is controlled by a microprocessor
controller.
[0018] The present invention is based on the application of a new
type of compressor set and heat exchanger. The new type of
refrigerating compressor set can control the opening ratio of the
refrigerating/cooling medium valve devices according to the working
parameters provided by the sensors, or change the working frequency
of the input power supply according to the working parameters
provided by the sensors, so as to regulate the operating speed of
the motor to adjust the output refrigerating capacity of the
refrigerating installation. This compressor set is different from
the traditional compressor set in that it adopts the magnetic
suspension bearings, so it does not need the traditional
lubricating oil and the corresponding circulating system and
cooling system, and it does not pollute the heat exchanger and
affect the efficiency of the heat exchange due to the existence of
the lubricating oil. The oil-free compressor facilitates the use of
full liquid evaporator. Furthermore, the compressor set integrates
a control means of digital circuit, and can monitor and adjust the
operating condition of the compressor in real time and allow each
refrigerating modular unit to work in balance without depending on
the outside control system. The heat exchanger used in the
invention is a plate heat exchanger having the full liquid
evaporation function. In all kinds of evaporators, the full liquid
evaporation is a heat exchange process of high efficiency, in which
the refrigerating medium channel is immersed in the liquid cryogen,
so that the heat exchange can be carried out under a very little
temperature difference. The new type of heat exchanger of the
invention combines the operating principle of full liquid
evaporator and the compact structure of plate heat exchanger, and
incorporates with the economizer, thereby obtaining a heat exchange
device with higher efficiency.
[0019] In general, the present invention apply the abovementioned
new techniques and control the circulation flow of the
refrigerating and cooling medium by combining the viable frequency
control technique, therefore, it not only can change the
refrigerating output of the refrigerating modular unit by
controlling the working frequency of the input power, but also can
make the working flow of the refrigerating and cooling medium to be
consistent with the refrigerating capacity, so that reduce the
running power of the water pump or the blower fan when the
compressor set or the refrigerating installation is running with
low load, and finally decrease the power consumption of the air
conditioning system and improve the control level to make the
control more convenient.
DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 shows the operating principle of the modular unit of
the invention.
[0021] FIG. 2 is an installation diagram of the modular unit of the
invention.
[0022] FIG. 3 is a block diagram showing the control principle of
the modular unit of the invention.
[0023] FIG. 4 is a block diagram showing the control principle of
the refrigerating installation of the invention.
[0024] FIG. 5 is an installation scheme of the sensing system of
the refrigerating installation.
DESCRIPTION OF THE SYMBOLS IN THE DRAWINGS
[0025] 1 compressor set [0026] 1A motor [0027] 1B compressor [0028]
2 gas-liquid separator [0029] 3 electric control box [0030] 4
evaporator (plate heat exchanger of full liquid evaporation type)
[0031] 41 core of the evaporator [0032] 42 shell of the evaporator
[0033] 5 discharge collecting tube of the refrigerating medium
[0034] 6 flow control valve of the refrigerating medium [0035] 7
inlet collecting tube of the refrigerating medium [0036] 8
throttling expansion device [0037] 9 dry filter [0038] 10 condenser
[0039] 11 flow control valve of the cooling medium [0040] 12
discharge collecting tube of the cooling medium [0041] 13 inlet
collecting tube of the cooling medium [0042] 14 economizer [0043]
14A heat exchange tube [0044] 15 expansion valve [0045] 18
microprocessor controller of the compressor [0046] 19 temperature
sensor of the refrigerating medium [0047] 20 sensor for pressure
difference between supply and return of the refrigerating medium at
the installation side [0048] 21 sensor for pressure difference
between supply and return of the refrigerating medium at the load
side [0049] 22 sensor for pressure difference between supply and
return of the cooling medium at the installation side [0050] 23
variable frequency regulator of the delivery pump for refrigerating
medium (transducer) [0051] 24 variable frequency regulator of the
delivery pump for cooling medium (transducer) [0052] 25 master
controller [0053] 26 suction pressure sensor [0054] 27 discharge
pressure sensor [0055] 28 magnetic bearing sensor
DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION
[0056] The present invention is a modular combined refrigerating
installation (refer to as combined refrigerating installation
hereafter) composed of multiple refrigerating modular units (refer
to as modular unit hereafter). For example, FIGS. 1 and 2 are the
operating principle of a refrigerating modular unit. Each modular
unit has a refrigerating cycle, which includes a refrigerating
compressor set 1, an evaporator 4 and a condenser 10; Each modular
unit has an inlet collecting tube 7 and a discharge collecting tube
5 for the flow of refrigerating medium, and the collecting tubes
connect with the inlet port and outlet port of medium liquid of the
evaporator 4 to constitute a cycle channel of the refrigerating
medium liquid. When a plurity of modular units are combined, these
collecting tubes link orderly to form a common channel of the
refrigerating medium liquid in the combined refrigerating
installation, and the evaporator 4 of each modular unit is
connected parallelly to the common channel.
[0057] A flow control valve 6 of the refrigerating medium which can
be regulated by proportional integral (e.g. the electric butterfly
valve made by Danfoss company) is mounted between the inlet
collecting tube 7 of the refrigerating medium and the port of the
evaporator 4. When the output refrigerating parameters of
compressor 1 change, the flow control valve 6 regulates the opening
ratio of the valve simultaneously to adjust the flow of the
refrigerating medium through the evaporator and make the working
flow consistent with the change of output refrigerating capacity of
the compressor.
[0058] Each modular unit has an inlet collecting tube 13 and a
discharge collecting tube 12 for the cooling medium liquid, and the
collecting tubes connect with the inlet/outlet ports of cooling
medium liquid of the condenser 10 to constitute a common channel of
the cooling medium liquid; When a plurality of refrigerating
modular units are combined, the collecting tubes link orderly to
form a common channel of the cooling medium liquid in the
refrigerating installation, and the condenser 10 of each modular
unit is connected parallelly to the common channel; A cooling
medium flow control valve 11 which can be regulated by proportional
integral is mounted between the collecting tube of the cooling
medium and the port of the condenser 10; The flow control valve 11
cooperate with the compressor 1B in a modular unit, and when the
output refrigerating capacity of the compressor changes, the flow
control valve 11 regulates the opening ratio of the valve
simultaneously to adjust the flow of cooling medium of the
condenser 10 and make the working flow consistent with the change
of output refrigerating capacity of the compressor.
[0059] The evaporator 4 as shown is a plate heat exchanger of full
liquid evaporation type, which is composed of an inner core 41 and
an outer shell 42, said core 41 is formed by welding a certain
number of metal plates with certain geometric shape according to a
certain rule; said outer shell 42 is a barrel shaped container with
a circle or square section; two or more kinds of medium flowing
channels are provided in said evaporator 4, they are isolated from
each other. The channel between the core 41 and shell 42 is the
channel for cryogen, and the cryogen enters into the evaporator 4
after throttling expansion to submerge the core 41, so that the
refrigerating medium flowing inside the core 41 is cooled, while
the liquid cryogen absorb the heat of the refrigerating medium to
be evaporated into gas.
[0060] An economizer 14 is provided in each modular unit. The
liquid cryogen from the condenser 10 is divided into two parts, one
part pass through the dry filter 9 and is throttled by the
expansion valve 15, and then super-cool the other part (pass
through the heat-exchanging tube 14A) and evaporates. The cryogen
after evaporation enters into the suction port of intermediate
pressure of the condenser 1B due to the pressure higher than the
outlet pressure of the cryogen in the evaporator; This economizer
cycle can increase the refrigerating capacity and the refrigerating
efficiency of unit.
[0061] A liquid level control throttling expansion device 8 (e.g.
the thermoelectric type expansion valve made by Sporlan company) is
mounted between the condenser 10 and the full liquid evaporator 4
to control the height of the liquid level of cryogen. When the
refrigerating load decrease and the liquid level of cryogen
increase in the evaporator 4 since the cryogen can not be fully
evaporated, the opening ratio of the throttling expansion device 8
is decreased to reduce the supply of the cryogen. Whereas, the
supply of the cryogen is increased. The throttling expansion device
may be a floating ball type expansion valve, a thermoelectric type
expansion valve or an electronic expansion valve, and the like.
[0062] A gas-liquid separator 2 is mounted between the suction port
of the compressor 17 and the evaporator 4 to separate the liquid
drops which are not fully evaporated and carried by the cryogen
steam from the evaporator 4, wherein the gaseous cryogen is
absorbed by the compressor 1B (see FIG. 3), while liquid cryogen
returns to the evaporator 4.
[0063] The working process of the system is as follows: the high
pressure gaseous cryogen discharged from the compressor 1 is
condensed to liquid cryogen in the condenser 10. After dried and
filtrated by the dry filter 9, the cryogen is divided into main
flow and branch flow, wherein the branch flow of less flow is
throttled with the expansion valve 15 (e.g. the thermal expansion
valve made by Danfoss company), and enters the economizer 14. The
cryogen in the branch flow cools the cryogen in the main flow, i.e.
in the heat exchanging tube 14A, to further decrease the degree of
super-cooling of the cryogen in the heat exchanging tube 14A, so
that increase the refrigerating capacity of unit flow rate. The
branch flow cryogen discharged from the economizer 14 returns to
the intermediate pressure suction port of the compressor 1 and is
compressed by the compressor 1. The main flow cryogen is throttled
by the expansion valve 8 and enters into the evaporator 4, in which
it absorbs the heat of the refrigerated water to be evaporated into
gas. The gaseous cryogen returns to the suction port 17 of the
condenser through the gas-liquid separator 2, and then is
compressed by the compressor. These completed a cycle process. When
a plurality of refrigerating modular units are combined, the
inlet/discharge collecting tubes for the refrigerating medium and
the cooling medium join orderly to form the consecutive channels
respectively, and these channels serve as the inlet or outlet
common channel for refrigerating/cooling medium respectively in
each refrigerating modular unit. The air cooling refrigerating
modular unit has the same operation principle except that the
condenser 10 is a finned coil condenser (not shown), and does not
need the collecting tubes 12 and 13.
[0064] As shown in FIG. 3, the used refrigerating compressor unit 1
(e.g. the TT300 refrigerating compressor made by TURBOCOR company)
includes an adjustable frequency motor 1A and a compressor 1B with
magnetic suspension bearings; the compressor 1B may change the
working frequency of the power supply or other working parameters
to adjust the operating speed, thereby regulating the refrigerating
capacity, and the compressor 1B is a oil-free type refrigerating
compressor which does not need any lubricating oil.
[0065] A discharge pressure sensor 27 (e.g. the pressure sensor
made by Danfoss company) is mounted at the discharge port of the
compressor 1B to transfer the pressure information for controlling
the opening ratio of the flow control valve 11 of refrigerating
medium. When the output load of the compressor 1B decreases, and/or
the decrease of the temperature of cooling medium results in the
decrease of the discharge pressure of the compressor, the
controller 18 decreases the opening ratio of the flow control valve
11 of cooling medium to reduce the supply of cooling medium; and
when the output load of the compressor 1B increases, and/or the
increase of the temperature of cooling medium results in the
increase of the discharge pressure, the controller 18 increases the
opening ratio of the flow control valve 11 of cooling medium to
increase the supply of cooling medium, thereby maintaining a stable
discharge pressure.
[0066] Each magnetic bearing sensors 28 (e.g. the TT300 magnetic
bearing sensor provided by TURBOCCOR company) is mounted at the
front and back radial magnetic bearings of the compressor 1B
respectively. According to the bearing magnetic strength parameters
collected by the magnetic bearing sensor 28, the microprocessor
controller 18 (e.g. the TT300 compressor controller made by
TURBOCOR company) instruct the motor and magnetic bearing
controller to increase the voltage of the magnetic bearing work
power supply when the magnetic strength decreases; and decrease the
voltage of the magnetic bearing work power supply when the magnetic
strength is too high, thereby maintaining the normal working
condition of the magnetic bearings.
[0067] A suction pressure sensor 26 (e.g. the pressure sensor made
by Danfoss company) is mounted at the suction port 17 of the
compressor to transfer the pressure information for controlling the
opening ratio of the flow control valve 6 of refrigerating medium;
The compressor set 1 is integrated with a microprocessor controller
18, and when the load decrease, the opening ratio of the flow
control valve 6 of refrigerating medium decrease and the flow rate
decrease so that the suction pressure of the compressor 1B
decrease, the information of the decrease of the pressure is
transferred to the controller 18 by the sensor 26, and the
controller 18 instructs the motor and magnetic bearing controller
to decrease the frequency of input power supply of motor 1A,
thereby decreasing the operating speed of the motor and reducing
the refrigerating capacity of the compressor; Or if the load
increases, the reverse process should be followed.
[0068] As shown in FIGS. 4 and 5, a refrigerating water temperature
sensor 19 (e.g. the temperature sensor made by Johnson company) is
used to collect and transfer the refrigerating water temperature
parameters of the installation for controlling the opening ratio of
flow control valve 6 of the refrigerating medium in a modular unit.
In the combined refrigerating installation, a master controller 25
(e.g. MV6 controller made by Multistack company) for the combined
refrigerating installation is used to control the operation of each
modular unit by collecting the refrigerating water temperature
parameters of installation with the refrigerating water temperature
sensor 19 and calculating the load required by the refrigerating
system. When the refrigerating water temperature increases as the
load of system increases, so the opening ratio of the flow control
valve 6 of refrigerating medium in the modular unit which is lastly
started is increased or the flow control valve of refrigerating
medium of the next modular unit is opened, and the microprocessor
controller 18 of compressor is instructed to start the
corresponding compressor. If the temperature of the refrigerating
medium decreases as the load required by the system decreases, the
inverse process should be followed.
[0069] There are also a sensor 20 for pressure difference between
supply and return at the unit side of the refrigerating medium
system and a sensor 21 for pressure difference between supply and
return at the load side (e.g. the pressure difference sensor made
by HUBA company) to collect and transfer the parameters of pressure
difference between supply and return for calculating and
controlling the working frequency of the delivery pump. The master
controller 25 of the combined refrigerating installation collects
the parameters of the sensor 20 for pressure difference between
supply and return at the installation side (e.g. the pressure
difference sensor made by HUBA company) and of the sensor 21 for
pressure difference between supply and return at the load side
(e.g. the pressure difference sensor made by HUBA company) of the
refrigerating medium system for calculating and controlling the
working frequency of the delivery pump. When the two pressure
difference values decrease as the system load increase, the master
controller increases the working frequency of transducers 23 for
one or more delivery pumps of the refrigerating medium (e.g. the
transducer made by Danfoss company) to increase the circulation
flow of the refrigerating medium so that be consistent with the
required load of the system; If the two pressure difference values
increase as the system load decreases, the master controller
decrease the working frequency of transducers 23 for one or more
delivery pumps of the refrigerating medium to decrease the
circulation flow of the refrigerating medium so that be consistent
with the required load of the system.
[0070] There is a sensor 22 for pressure difference between supply
and return at the installation side of the cooling medium system
(the pressure difference sensor made by HUBA company) to calculate
and control the working frequency of the delivery pump. The master
controller 25 collect the parameters of the sensor 22 for pressure
difference between supply and return at the installation side of
the refrigerating medium system for calculating and controlling the
working frequency of the delivery pump. When the pressure
difference value decreases as the system load increases, the master
controller increases the working frequency of transducers 24 for
one or more delivery pumps of the cooling medium (e.g. the
transducer made by Danfoss company) to increase the circulation
flow of the cooling medium so that be consistent with the required
load of the system; If the pressure difference value increases as
the system load decreases, the master controller decreases the
working frequency of transducers 24 for one or more delivery pumps
of the cooling medium to decrease the circulation flow of the
cooling medium so that be consistent with the required load of the
system.
[0071] The automatic, balanced and energy-saving operation mode may
be: the master microprocessor controller 25 which is mounted in the
electric control box 3 of one of the refrigerating modular units
monitors the microprocessor controllers 18 on each compressor, and
detects the working temperature of the refrigerating medium by the
temperature sensor 19 of refrigerating medium of the refrigerating
installation. When the temperature of the refrigerating medium
flowed out of the installation decreases as the system load
decreases, the master controller 25 firstly decrease the opening
ratio of the flow control valve 6 of refrigerating medium of the
modular unit of which the compressor has the most long cumulating
running time among all the running compressors, to decrease the
flow of refrigerating medium and decrease the suction pressure of
the compressor, so that the controller 18 decrease the working
frequency of the compressor set 1 to decrease the work output of
the compressor set. When the compressor output load decreases, the
discharge pressure of the compressor also decreases, thus the
opening ratio of the flow control valve 11 of cooling medium is
decreased at the same time to reduce the supply of the cooling
medium. With the decrease of the load required by the system, the
work output of this compressor set 1 will decrease continuously and
finally it is closed completely. At this time, the operation of
next compressor begin to change by the same process; And when the
temperature of refrigerating medium flowed out of the installation
increases as the load required by the system increases, according
to an inverse process to the above method, the compressor having
the least cumulating running time in all the compressors in rest
state is started, and the flow control valve of the refrigerating
medium in the modular unit, on which said compressor is mounted, is
opened simultaneously with the opening ratio of said flow control
valve increased continuously. Due to the increase of the flow of
refrigerating medium, the suction pressure of the compressor
increases, and the controller 18 increases the working frequency of
the compressor to increase the output of the compressor to the
maximum state. When the output of the compressor increases, the
discharge pressure of the compressor increases, so that the opening
ratio of the flow control valve 11 of cooling medium increases, and
the supply of the cooling medium increases. With the increase of
the load required by the system, the working output of this
compressor will increase continuously until to the maximum state,
and then the next compressor set is started. Thus, the installation
is operated in a balanced and energy-saving mode.
* * * * *