US20030037919A1

US20030037919A1 - Connected chilling-heating system

Info

Publication number: US20030037919A1
Application number: US10/218,909
Authority: US
Inventors: Takashi Okada; Masakazu Fujimoto
Original assignee: Individual
Current assignee: Ebara Corp
Priority date: 2001-08-17
Filing date: 2002-08-15
Publication date: 2003-02-27
Also published as: CN1417535A; CN1239870C

Abstract

The present invention provides a connected chilling-hating system capable of saving delivering power during reduced load periods. The system comprises load-side equipment, a set of chiller-heater modules connected in parallel, and a cold/hot water pipe connected between the load-side equipment and the set of chiller-heater modules to form a loop,

wherein each chiller-heater module is connected to a cold/hot water inlet pipe for supplying cold/hot water to the module and a cold/hot water outlet pipe for collecting cold/hot water from the module, said inlet or outlet pipe having a flow valve,

wherein the flow control of cold/hot water is accomplished by opening or closing the respective flow valves placed on the cold/hot water inlet pipes or the cold/hot water outlet pipes of the chiller-heater modules in response to the number of chiller-heater modules in operation.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a connected chilling-heating system. More specifically, the present invention relates to a connected chilling-heating system comprising a set of chiller-heater modules connected in parallel to form an integrated unit, each module having a compressor, a cooler, a condenser and a throttling system to form a cold/hot water cycle. The connected chilling-heating system of the present invention allows inlet/outlet temperature control, flow control and delivery pressure control of cold/hot water.

A prior art connected chilling-heating system is illustrated by reference to the overall schematic view shown in FIG. 4. The symbols found in FIG. 4 are defined as follows:

1: an inlet connecting pipe;

2: a pump for cold/hot water or brine;

3, 4, 5, 6, 7: a chiller-heater module;

8: an outlet connecting pipe;

9: inlet temperature;

10: outlet temperature;

11: a supply header;

12: a return header;

13: a cold/hot water bypass valve;

14, 15: a load heat exchanger such as an air conditioner, etc.;

16, 17: a load control valve;

18: a pump for cooling water or heat source water (cooling/heat source water);

19: a circulating tank for cooling/heat source water;

20: a one-way source for cooling/heat source water;

21: a one-way receiver for cooling/heat source water; and

22, 23, 24, 25: a one-way/circulation switching valve.

As shown in the figure, the connected chilling-heating system comprises load-

side equipment

14 and 15 such as an air conditioner, a set of chiller-heater modules 3 to 7 connected in parallel, and a cold/hot water pipe connected between the load-side equipment and the set of chiller-heater modules to form a loop. The set of chiller-heater modules is connected to a cooling/heat source water pipe, in addition to the cold/hot water pipe. The cold/hot water pipe comprises a cold/hot water supply pipe for supplying cold/hot water from the chiller-heater modules to the load-side equipment and a cold/hot water return pipe for returning cold/hot water from the load-side equipment to the chiller-heater modules. Likewise, the cooling/heat source water pipe comprises a cooling/heat source water return pipe for collecting cooling/heat source water from the chiller-heater modules and a cooling/heat source water supply pipe for supplying cooling/heat source water to the chiller-heater modules. In the system shown in FIG. 4, supply header 11 and return header 12 are placed on the cold/hot water supply pipe and the cold/hot water return pipe, respectively.

In this system, cold/hot water or brine is pumped by

pump

2 from return header 12 into chiller-

heater modules

3, 4, 5, 6 and 7, where cold/hot water or brine is chilled or heated. At this stage, cold/hot water or brine receives temperature control to ensure constant outlet temperature 10 of cold/hot water mixed in outlet connecting pipe 8. Cold/hot water or brine is then delivered from supply header 11 to the individual load-

side equipment

14 and 15.

FIG. 4 shows chilling operation where cold water or brine is chilled. When the chilling load starts to decrease in this operation, the volume of cold water or brine delivered to the load heat exchangers is reduced by throttling

load control valves

16 and 17, while the number of chiller-heater modules in operation is reduced by number control processing. However, if chiller-

heater modules

6 and 7 are stopped, cold water or brine chilled in the operating chiller-

heater modules

3, 4 and 5 is combined in outlet connecting pipe 8 with cold water or brine passed at inlet temperature 9 through the stopped chiller-

heater modules

6 and 7, whereby outlet temperature 10 becomes higher than it is during fleet operation. In this case, in order to attain the same outlet temperature 10 as when fleet operation is performed (all of chiller-heater modules 3-7 are operated), the respective temperatures at the outlets of the operating chiller-

heater modules

3, 4 and 5 must be controlled such that they become lower than when fleet operation is done.

For example, in a case where

inlet temperature

9 is 10.0° C. and outlet temperature 10 should be regulated to 7.0° C., the respective temperatures at the outlets of chiller-

heater modules

3, 4 and 5 must be set to 5.0° C.

Likewise, cooling/heat source water also passes through the chiller-heater modules at rest as well as the modules in operation.

This prior art chilling-heating system involves the following problems:

(i) in order to ensure

constant outlet temperature

10, another control system is required for changing the temperature setting of cold/hot water at the inlet or outlet of each chiller-heater module in accordance with the number of operating chiller-heater modules, in addition to a control system for maintaining the temperature of cold/hot water at the inlet or outlet of each chiller-heater module at the intended temperature;

(ii) there occurs a decrease in C.O.P (coefficient of performance) due to a reduced temperature setting (elevated temperature setting in heating operation) at the inlet or outlet of each chiller-heater module in operation, which leads to unwanted overconsumption of energy;

(iii) extra delivering power is required because

load control valves

16 and 17, when throttled in response to a decrease in load, cause an excessive amount of cold/hot water or brine to pass through cold/hot water bypass valve 13;

(iv) for the same reason, extra delivering power is required by the cooling water system during cold water production or by the heating water system during hot water production (where a heat pump is driven) in response to a decrease in the number of operating chiller-heater modules during reduced load periods; and

(v) internal pipes in the chiller-heater modules at rest are excessively stained.

To overcome the above problems involved in the prior art, the present invention is aimed at providing a connected chilling-heating system that not only ensures the intended temperature and optimum flow of cold/hot water supplied to load-side equipment without changing the temperature setting at the inlet or outlet of each chiller-heater module, but also allows power saving in delivering cooling/heat source water, when some of the connected chiller-heater modules are stopped to control the number of chiller-heater modules in operation.

SUMMARY OF THE INVENTION

In order to achieve the aim mentioned above, the present invention provides:

(1) a connected chilling-heating system comprising load-side equipment, a set of chiller-heater modules connected in parallel, and a cold/hot water pipe connected between the load-side equipment and the set of chiller-heater modules to form a loop,

wherein the set of chiller-heater modules is connected to a cooling/heat source water pipe, in addition to the cold/hot water pipe,

wherein the cold/hot water pipe comprises a cold/hot water supply pipe for supplying cold/hot water from the chiller-heater modules to the load-side equipment and a cold/hot water return pipe for returning cold/hot water from the load-side equipment to the chiller-heater modules,

wherein the cooling/heat source water pipe comprises a cooling/heat source water return pipe for collecting cooling/heat source water from the chiller-heater modules and a cooling/heat source water supply pipe for supplying cooling/heat source water to the chiller-heater modules,

wherein each chiller-heater module is connected to a cold/hot water inlet pipe for supplying cold/hot water to the module and a cold/hot water outlet pipe for collecting cold/hot water from the module, said inlet and/or outlet pipe having a flow valve,

wherein the system has a means for regulating the number of chiller-heater modules in operation depending on chilling/heating load, and the flow control of cold/hot water is accomplished by opening or closing the respective flow valves placed on the cold/hot water inlet pipes and/or the cold/hot water outlet pipes of the chiller-heater modules in response to the number of chiller-heater modules in operation.

The present invention further includes the following preferred embodiments:

(2) the connected chilling-heating system of (1) above, which further comprises a speed controller-equipped pump or a plurality of pumps placed on the route of the cold/hot water pipe between the set of chiller-heater modules and the load-side equipment,

wherein a variation in discharge pressure of the pump(s) or differential pressure between the cold/hot water supply pipe and the cold/hot water return pipe, produced by opening or closing the flow valves, is adjusted to ensure optimum pressure by the action of the speed controller equipped on the pump or by controlling the number of pumps in operation;

(3) the connected chilling-heating system of (2) above, which further comprises a bypass channel connecting the cold/hot water supply pipe and the cold/hot water return pipe, said bypass channel being placed on the route of the cold/hot water pipe between the set of chiller-heater modules and the load-side equipment,

wherein the bypass flow through the bypass channel is adjusted to approach zero by the action of the speed controller equipped on the pump or by controlling the number of pumps in operation;

(4) the connected chilling-heating system of (2) above, which further comprises a cold/hot water supply header placed on the cold/hot water supply pipe and a cold/hot water return header placed on the cold/hot water return pipe,

wherein a variation in differential pressure between these two headers, produced by opening or closing the flow valves, is adjusted to ensure optimum pressure by the action of the speed controller equipped on the pump or by controlling the number of pumps in operation;

(5) the connected chilling-heating system of (3) above, which further comprises a cold/hot water supply header placed on the cold/hot water supply pipe, a cold/hot water return header placed on the cold/hot water return pipe, and a bypass channel connecting these two headers,

(6) the connected chilling-heating system of any one of (1) to (5) above, wherein each chiller-heater module is further connected to a cooling/heat source water inlet pipe for supplying cooling/heat source water to the module and a cooling/heat source water outlet pipe for collecting cooling/heat source water from the module, said inlet and/or outlet pipe having a flow valve, wherein the flow control of cooling/heat source water is accomplished by opening or closing the respective flow valves placed on the cooling/heat source water inlet pipes and/or the cooling/heat source water outlet pipes of the chiller-heater modules in response to the number of chiller-heater modules in operation;

(7) the connected chilling-heating system of (6) above, which further comprises a speed controller-equipped pump or a plurality of pumps placed on the route of the cooling/heat source water pipe,

wherein a variation in discharge pressure of the pump(s) or differential pressure between the cooling/heat source water return pipe and the cooling/heat source water supply pipe, produced by opening or closing the flow valves, is adjusted to ensure optimum pressure by the action of the speed controller equipped on the pump or by controlling the number of pumps in operation; and

(8) the connected chilling-heating system of (7) above, which further comprises a bypass channel connecting the cooling/heat source water supply pipe and the cooling/heat source water return pipe, said bypass channel being placed on the route of the cooling/heat source water pipe,

wherein the bypass flow through the bypass channel is adjusted to approach zero by the action of the speed controller equipped on the pump or by controlling the number of pumps in operation.

This specification includes part or all of the contents as disclosed in the specification and/or drawings of Japanese Patent Application No. 2001-247796, which is a priority document of the present application.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an overall schematic view showing a chilling-heating system according to an embodiment of the present invention, which comprises a set of connected chiller-heater modules and load-side equipment connected to the modules. [0053]
FIG. 2 is an overall schematic view showing a chilling-heating system according to another embodiment of the present invention, which comprises a set of connected chiller-heater modules and load-side equipment connected to the modules. [0054]
FIG. 3 is a conceptual view of individual chiller-heater modules used in the present invention. [0055]
FIG. 4 is an overall schematic view of a prior art chilling-heating system, which comprises a set of connected chiller-heater modules and load-side equipment connected to the modules.[0056]

DETAILED DESCRIPTION OF THE INVENTION

A preferred embodiment of the present invention is a connected chilling-heating system comprising a set of chiller-heater modules connected in parallel, [0057]
wherein the inlet or outlet temperature of cold/hot water is controlled in each chiller-heater module, [0058]
wherein the number of chiller-heater modules in operation is controlled in response to a change in load, [0059]
wherein the total flow rate of cold/hot water passed through the set of chiller-heater modules is controlled by opening or closing the respective flow valves placed on the cold/hot water inlet pipes or the cold/hot water outlet pipes of the chiller-heater modules in response to the number of chiller-heater modules in operation, [0060]
wherein an increase in discharge pressure of the pump(s) or differential pressure between the cold/hot water supply pipe and the cold/hot water return pipe, produced by opening or closing the flow valves, is adjusted to ensure optimum pressure by the action of the speed controller equipped on the pump or by controlling the number of pumps in operation, whereby the waste of delivering power is avoided to save energy. [0061]
Another preferred embodiment of the present invention is a connected chilling-heating system comprising a set of chiller-heater modules connected in parallel, [0062]
wherein the inlet or outlet temperature of cold/hot water is controlled in each chiller-heater module, [0063]
wherein the number of chiller-heater modules in operation is controlled in response to a change in load, [0064]
wherein the total flow rate of cooling/heat source water passed through the set of chiller-heater modules is controlled by opening or closing the respective flow valves placed on the cooling/heat source water inlet pipes or the cooling/heat source water outlet pipes of the chiller-heater modules in response to the number of chiller-heater modules in operation, [0065]
wherein an increase in discharge pressure of the pump(s) or differential pressure between the cooling/heat source water supply pipe and the cooling/heat source water return pipe, produced by opening or closing the flow valves, is adjusted to ensure optimum pressure by the action of the speed controller equipped on the pump or by controlling the number of pumps in operation, whereby the waste of delivering power is avoided to save energy. [0066]
Next, the present invention will be illustrated by reference to drawings. [0067]
FIG. 1 shows an overall schematic view of a chilling-heating system according to an embodiment of the present invention, which comprises 5 connected chiller-heater modules and 2 load-side equipments connected to the modules. FIG. 1 is explained below in terms of chilling operation by way of example. [0068]
This figure also contains specific information on the temperature and flow rate of cold water during a reduced load period, given that the temperature of cold water or brine in each chiller-heater module is preset to 7.0° C. and the flow rate of cold water or brine per chiller-heater module is represented by Q. [0069]
[0070] Symbols 1 to 25 found in FIG. 1 are as defined above in FIG. 4. Symbols 26 to 41 are defined as follows:
[0071] 26, 27, 28, 29, 30: a flow valve for cold/hot water;
[0072] 31, 32, 33, 34, 35: a flow valve for cooling/heat source water;
[0073] 36: a pumping pressure detector for cold/hot water or brine;
[0074] 37: a pressure controller;
[0075] 38: a speed controller for cold/hot water or brine;
[0076] 39: a pumping pressure detector for cooling/heat source water;
[0077] 40: a pressure controller; and
[0078] 41: a speed controller for cooling/heat source water.
The action of the connected chilling-heating system shown in FIG. 1 is explained. In a case where chiller-[0079] heater modules 6 and 7 are stopped to control the number of chiller-heater modules in response to a decrease in load, flow valves 29 and 30 are closed to prevent the flow of cold water or brine into chiller- heater modules 6 and 7 at rest. As a result, the temperature of cold water or brine is maintained at 7.0° C. at the outlets of the individual chiller- heater modules 3, 4 and 5 in operation, which in turn ensures outlet temperature 10 of 7.0° C. Thus, cold water or brine at 7.0° C. can be supplied to the load-side equipment.
Meanwhile, the [0080] closed flow valves 29 and 30 elevate the discharge pressure of pump 2. This elevated discharge pressure is detected by pumping pressure detector 36 and then transmitted to pressure controller 37, which in turn controls speed controller 38 to reduce the discharge pressure of pump 2. In this way, extra delivering power can be saved. Also, load control valves 16 and 17 allow the flow of excess cold/hot water to pass through cold/hot water bypass valve 13 when the load control valves are throttled in response to a decrease in load. This flow through cold/hot water bypass valve 13 is able to approach zero by reducing the discharge quantity of pump 2, which leads to a further saving in delivering power.
Regarding cooling water, if chiller-[0081] heater modules 6 and 7 are stopped, flow valves 34 and 35 are closed to prevent the flow of cooling water into the chiller-heater modules at rest.
Since the [0082] closed flow valves 34 and 35 elevate the discharge pressure of pump 18, the discharge pressure is detected by pumping pressure detector 39 and then transmitted to pressure controller 40, which in turn controls speed controller 41 to reduce the discharge pressure of pump 18. In this way, extra delivering power can also be saved in the cooling water system.
FIG. 2 shows an overall schematic view of a chilling-heating system according to another embodiment of the present invention, which is different from FIG. 1. [0083]
In the system of FIG. 2, [0084] symbols 1 to 35 are as defined in FIG. 1. Additional symbols are defined as follows:
[0085] 2′: a pump for cold/hot water or brine;
[0086] 18′: a pump for cooling/heat source water;
[0087] 36′: a header differential pressure detector;
[0088] 37′: a differential pressure controller;
[0089] 39′: a differential pressure transmitter for cooling water; and
[0090] 40′: a differential pressure controller.
In the case of this system, the header differential pressure between [0091] supply header 11 and return header 12 is detected by differential pressure detector 36′, instead of detecting the discharge pressure of pump 2. The detected differential pressure is then transmitted to differential pressure controller 37′, which in turn controls the number of pumps 2 and 2′. In this way, extra delivering power can be saved. Although FIG. 2 shows an embodiment including two pumps for cold/hot water or brine, the same can be applied to the case of using more than two pumps. Likewise, the same can also be applied to the case of using secondary pumps 42 and 43 for cold/hot water or brine.
Regarding cooling/heat source water for the chiller-heater modules, the differential pressure between the cooling water supply pipe and the cooling water return pipe is detected by [0092] differential pressure controller 39′, instead of detecting the discharge pressure of the pump for cooling/heat source water. The detected differential pressure is then transmitted to differential pressure controller 40′, which in turn controls the number of pumps 18 and 18′. In this way, extra delivering power can also be saved in the cooling/heat source water system. Although FIG. 2 shows an embodiment including two pumps for cooling/heat source water, the same can be applied to the case of using more than two pumps.
Incidentally, FIGS. 1 and 2 illustrate a system in which a supply header and a return header for cold/hot water are provided at a supply pipe and a return pipe for cold/hot water, respectively. However, the present invention may also apply to a system in which headers are not provided. For example, in the system of FIG. 1, a bypass channel is provided directly between the supply pipe and the return pipe for cold/hot water without providing [0093] supply header 11 and return header 12, and discharge quantity of pump 2 may be regulated so as to approach the flow of cold/hot water through the bypass channel to zero. Further, in the system of FIG. 2, a differential pressure detector 36′and a bypass channel may be provided directly between the supply pipe and the return pipe for cold/hot water without providing supply header 11 and return header 12.
Although an explanation was given on chilling operation where cold water or brine was chilled, the same can be said for heating operation where hot water is heated. [0094]
FIG. 3 shows a conceptual view of individual chiller-heater modules used in the present invention. [0095]
In FIG. 3, [0096] symbols 44, 45, 46 and 47 represent a cooler, a compressor, a condenser and a throttling system, respectively.
The refrigeration cycle of the chiller-heater module shown in FIG. 3 is explained. A refrigerant gas vaporized in cooler [0097] 44 is compressed in compressor 45 and then introduced into condenser 46 to be cooled with cooling water 48 for liquefaction. The liquefied refrigerant is decompressed by throttling system 47 and then introduced into a refrigerating chamber in cooler 44, where the refrigerant absorbs heat from cold water or brine entering from inlet nozzle 1 and hence vaporizes itself again before entering a second refrigeration cycle. In this way, cold water or brine is chilled and then flows out of outlet nozzle 8.
According to the present invention, the use of the control mechanism as stated above enables a connected chilling-heating system to have the following features: [0098]
(i) no additional control system is required for changing the temperature setting (intended temperature) of cold/hot water at the inlet or outlet of each chiller-heater module even where the number of chiller-heater modules in operation is reduced as the result of load reduction; [0099]
(ii) a decrease in C.O.P (coefficient of performance) can be avoided because there is no need to reduce the temperature setting of cold/hot water at the inlet or outlet of each chiller-heater module in operation even where some of the chiller-heater modules are stopped, whereby cold/hot water can be supplied to the load-side equipment at the intended temperature; [0100]
(iii) delivering power can be saved because the optimum flow of cold/hot water and cooling/heat source water is ensured in response to a specific chilling or heating load; and [0101]
(iv) excessive staining of internal pipes in the chiller-heater modules at rest can be prevented. [0102]

Claims

What is claimed is:

1. A connected chilling-heating system comprising load-side equipment, a set of chiller-heater modules connected in parallel, and a cold/hot water pipe connected between the load-side equipment and the set of chiller-heater modules to form a loop,

2. The connected chilling-heating system of claim 1, which further comprises a speed-controller-equipped pump or a plurality of pumps placed on the route of the cold/hot water pipe between the set of chiller-heater modules and the load-side equipment,

wherein a variation in discharge pressure of the pump(s) or differential pressure between the cold/hot water supply pipe and the cold/hot water return pipe, produced by opening or closing the flow valves, is adjusted to ensure optimum pressure by the action of the speed controller equipped on the pump or by controlling the number of pumps in operation.

3. The connected chilling-heating system of claim 2, which further comprises a bypass channel connecting the cold/hot water supply pipe and the cold/hot water return pipe, said bypass channel being placed on the route of the cold/hot water pipe between the set of chiller-heater modules and the load-side equipment,

4. The connected chilling-heating system of claim 2, which further comprises a cold/hot water supply header placed on the cold/hot water supply pipe and a cold/hot water return header placed on the cold/hot water return pipe,

wherein a variation in differential pressure between these two headers, produced by opening or closing the flow valves, is adjusted to ensure optimum pressure by the action of the speed controller equipped on the pump or by controlling the number of pumps in operation.

5. The connected chilling-heating system of claim 3, which further comprises a cold/hot water supply header placed on the cold/hot water supply pipe, a cold/hot water return header placed on the cold/hot water return pipe, and a bypass channel connecting these two headers,

6. The connected chilling-heating system of claim 1, wherein each chiller-heater module is further connected to a cooling/heat source water inlet pipe for supplying cooling/heat source water to the module and a cooling/heat source water outlet pipe for collecting cooling/heat source water from the module, said inlet and/or outlet pipe having a flow valve,

wherein the flow control of cooling/heat source water is accomplished by opening or closing the respective flow valves placed on the cooling/heat source water inlet pipes and/or the cooling/heat source water outlet pipes of the chiller-heater modules in response to the number of chiller-heater modules in operation.

7. The connected chilling-heating system of claim 6, which further comprises a speed controller-equipped pump or a plurality of pumps placed on the route of the cooling/heat source water pipe,

wherein a variation in discharge pressure of the pump(s) or differential pressure between the cooling/heat source water return pipe and the cooling/heat source water supply pipe, produced by opening or closing the flow valves, is adjusted to ensure optimum pressure by the action of the speed controller equipped on the pump or by controlling the number of pumps in operation.

8. The connected chilling-heating system of claim 7, which further comprises a bypass channel connecting the cooling/heat source water supply pipe and the cooling/heat source water return pipe, said bypass channel being placed on the route of the cooling/heat source water pipe,