Title:
Ice storage constant temperature air conditioning system having divided refrigerant
Kind Code:
A1


Abstract:
An ice storage constant temperature air conditioning system having divided refrigerant has a refrigerant divider to divide refrigerant flow into two ducts. The first duct is connected to an evaporator to absorb a great amount of latent heat to generate refrigeration. The refrigerant flows to an ice storage refrigerant loop of an ice storage tank to store ice. The second duct directly sends the refrigerant to the ice storage refrigerant loop to store the ice. Hence the refrigerant can be fully used or used in a divided fashion. A condensate collection tray is provided below the evaporator to recycle heat of low temperature condensate during operation of air conditioning to automatically replenish the chill water of the ice storage tank. The refrigerant at the condensate outlet is cooled during ice storing or ice melting period to become a subcooling liquid refrigerant to enhance refrigeration effect.



Inventors:
Hsiao, Ming-jer (Nantou City, TW)
Hsiao, Chin-hsin (Nantou City, TW)
Application Number:
11/882919
Publication Date:
02/12/2009
Filing Date:
08/07/2007
Assignee:
NAN KAI INSTITUTE OF TECHNOLOGY
Primary Class:
International Classes:
F24F5/00
View Patent Images:



Primary Examiner:
ROGERS, LAKIYA G
Attorney, Agent or Firm:
Joe McKinney Muncy (Fairfax, VA, US)
Claims:
What is claimed is:

1. An ice storage constant temperature air conditioning system having divided refrigerant, comprising: a compressor to compress the refrigerant to become over-heated in a gas phase; a condenser to receive and cool the over-heated gas refrigerant to become a liquid phase; and a refrigerant divider to receive the cooled and liquid refrigerant through a liquid duct and automatically divide the liquid refrigerant into a first duct and a second duct; wherein the cooled and liquid refrigerant flows through the first duct and a heat exchanger located thereon to become a subcooling liquid refrigerant at a high pressure and a low temperature, the subcooling liquid refrigerant passing through an air conditioning expansion valve to become a saturated and mist type refrigerant in liquid and gas phases to enter an evaporator, the evaporator absorbing a great amount of latent heat and sensible heat to generate refrigeration, residual refrigerant entering an ice storage refrigerant loop to store ice; wherein the second duct delivers a portion of the cooling liquid refrigerant to the ice storage refrigerant loop after being expanded through an ice storage expansion valve to absorb a great amount of latent heat to store the ice; the refrigerant in the ice storage refrigerant loop being sent to the compressor through a gas duct to complete a refrigerant circulation cycle.

2. The ice storage constant temperature air conditioning system of claim 1, wherein the refrigerant divider closes the first duct to allow all of the refrigerant to flow into the second duct during a no load condition of a cooling room.

3. The ice storage constant temperature air conditioning system of claim 1, wherein the refrigerant divider controls the ratio of the refrigerant in the first duct and the second duct according to a room temperature during a low load condition of a cooling room so that the refrigerant amount in the first duct alters according to required amount of the refrigerant in the evaporator and the rest of the refrigerant is distributed to the second duct.

4. The ice storage constant temperature air conditioning system of claim 1, wherein the refrigerant divider closes the second duct to allow all of the refrigerant to generate a phase change and flow into the evaporator through the first duct during a full load condition of a cooling room.

5. The ice storage constant temperature air conditioning system of claim 1, wherein the refrigerant divider channels all of the refrigerant to the evaporator through the first duct and the heat exchanger melts the ice during a high load condition of a cooling room, and cooled energy in the ice stored in a no load condition and a low load condition of a cooling room is released.

6. The ice storage constant temperature air conditioning system of claim 1 further having a condensate collection tray located below the evaporator to recycle heat of low temperature condensate generated during operation of air conditioning to automatically replenish chill water in an ice storage tank of the system.

Description:

FIELD OF THE INVENTION

The present invention relates to an ice storage constant temperature air conditioning system and particularly to an ice storage technique that adopts divided refrigerant to allow a refrigerant system to divide and distribute the refrigerant according to the load of an air conditioning room to fully or partially use the refrigerant to effectively transfer energy and achieve optimum operation effect.

BACKGROUND OF THE INVENTION

When water is frozen to become ice the energy is stored to become “latent heat”. The latent heat in such an occasion is 79 KCAL/KG. A general air conditioning system has chill water at a maximum temperature about 15° C. Thus when the water of 15° C. is frozen to become ice of 0° C. the total energy being stored is 94 KCAL/KG.

The air conditioning system that adopts ice storage is based on a principle as follow: operate the compressor at a selected time period (such as off peak load or half peak load period) to form ice from the chill water and store the cooling energy of the compressor in the form of ice; during the peak load period in day time and the chill water (cooling air) is needed, but operation of the chill water device is undesirable (peak load time period), melt the ice to absorb the heat of the chill water at a constant temperature to cool the chill water; thus power consumption of air conditioning at the peak load period in the day time can be transferred to the night time. Namely melting of the ice can absorb the heat of the high temperature chill water to cool the chill water so that the power consumption of air conditioning at the peak load period in the day time can be transferred to the night time.

Refer to FIG. 1 for the refrigerant system of a conventional ice storage air conditioning system. It operates in such a way: when the returned chill water in an air conditioner (indoor device) is at a temperature above a set value of a return water temperature sensor, the system activates a compressor 11 to operate; the refrigerant is conveyed through an gas duct 19 to the compressor 11 and compressed to become an over-heated refrigerant in a gas phase at a high pressure and high temperature; then the refrigerant enters a condenser 12 to disperse heat to become cooling refrigerant in a liquid phase at a high pressure but a normal temperature; the refrigerant flows through a liquid duct 13 to a heat exchanger 14 to become a subcooling refrigerant in the liquid phase at a high pressure and a low temperature; through throttling of an expansion valve 15 the pressure of the refrigerant drops to become a saturated and mist type refrigerant in liquid and gas phases at a low pressure and low temperature; then the refrigerant enters an evaporator 16 to be vaporized to absorb a great amount of latent heat to be chilled; cooling air is sent out through an air conditioner 17 to an air conditioning room; the refrigerant absorbs heat to become low pressure at the normal temperature and flows to an ice storage refrigerant loop 18 of an ice storage tank to store ice for residual refrigerant; the refrigerant flowing through the ice storage refrigerant loop 18 returns to the compressor 11 through the gas duct 19 to complete a refrigerant circulation cycle.

The chill water flowing out of the air conditioner 17 is sent to a chill water side of the evaporator 16 through a chill water pump to become chill water at a low temperature (generally at 7□) to provide the air conditioner 17 to cool the heating load in the air conditioning room, thus complete a chill water circulation cycle.

The refrigerant has to flow through the evaporator 16 to enter the ice storage refrigerant loop 18 whether in the condition of a low cooling room or high cooling room. Hence the heat energy of all the refrigerant has to be transferred through the evaporator 16 to enter the ice storage refrigerant loop 18 no mater how much the refrigerant actually needed in the evaporator 16. It greatly reduces the ice storage efficiency in the condition of low cooling room.

Moreover, the ice storage constant temperature air conditioning system now on the market adopts an evaporator which discharges the condensate being generated. Hence water has to be replenished to the ice storage apparatus to achieve the ice storage effect. It is a waste of water in the air conditioning system.

SUMMARY OF THE INVENTION

Therefore the primary object of the present invention is to provide an ice storage constant temperature air conditioning system that adopts divided refrigerant. It has a refrigerant divider in a refrigerant system ahead an evaporator. The refrigerant divider controls flow amount and direction of the refrigerant. Flow of the refrigerant is divided into two ducts. One duct is connected to the evaporator and other duct is connected to an ice storage refrigerant loop of an ice storage tank. Hence the refrigerant can totally flow in the ice storage tank to store ice or the evaporator to melt the ice for air conditioning use, or partially flow to the ice storage tank and the evaporator. Thereby the system of the invention can divide and distribute the refrigerant according to the load of the air conditioning room to transfer heat energy. It can save energy and achieve an optimum air conditioning operation efficiency at a constant temperature.

Another object of the invention is to provide a condensate collection tray under the evaporator to cycle the heat of the low temperature condensate generated during operation of the air conditioning. It also can automatically replenish the chill water in the ice storage tank. Moreover, during storing ice or melting ice the refrigerant at the outlet of the condenser is cooled to become a subcooling liquid refrigerant to enhance refrigeration effect.

The ice storage constant temperature air conditioning system that adopts divided refrigerant according to the invention includes a compressor to compress refrigerant to become an over-heated refrigerant in a gas phase at a high pressure and high temperature, a condenser to receive the over-heated refrigerant in the gas phase and cool the refrigerant to become a liquid refrigerant at a high pressure and a normal temperature, a refrigerant divider to receive the cooling liquid refrigerant through a liquid duct and divide automatically the cooling liquid refrigerant into a first duct and a second duct. The first duct has a heat exchanger to transform the cooling liquid refrigerant to a subcooling liquid refrigerant at a high pressure and low temperature, then the subcooling liquid refrigerant flows to an air conditioning expansion valve to be expanded and become a saturated and mist type refrigerant in liquid and gas phases to enter an evaporator which absorbs a great amount of latent heat through evaporation to generate cooling effect; residual refrigerant flows to an ice storage refrigerant loop to generate refrigeration and store ice. The second duct is connected to the ice storage refrigerant loop through an ice storage expansion valve which expands the refrigerant to absorb a great amount of latent heat to store the ice. The refrigerant in the ice storage refrigerant loop finally returns to the compressor through a gas duct to complete one refrigerant circulation cycle. Thus the refrigerant can fully flow into the ice storage tank to store the ice or fully enter the evaporator to melt the ice to generate air conditioning, or partially flow to the ice storage tank and the evaporator.

The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings. The embodiments being discussed serve only for illustrative purpose and are not the limitation of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of the refrigerant system of a conventional ice storage air conditioning.

FIG. 2 is a schematic view of the refrigerant system of the ice storage air conditioning of the invention.

FIG. 3 is a schematic view of the apparatus of the invention.

FIG. 4 is a schematic view of the invention for distributing a low load of a cooling room and an ice storage refrigeration load in the condition of a low cooling room.

FIG. 5 is a schematic view of the invention for distributing a high load of a cooling room and an ice melting load in the condition of a high cooling room.

FIG. 6 is a Mollier chart of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Please refer to FIG. 2 for a refrigerant system of an ice storage air conditioning of the invention. When in use and the temperature of returned chill water of an air conditioner (indoor device) is above a set value of a return water temperature sensor, the system activates a compressor 21 to operate, and refrigerant in a gas duct 29 is compressed by the compressor 21 to become over-heated refrigerant in a gas phase at a high pressure and high temperature. The over-heated gas refrigerant enters a condenser 22 to disperse heat to become a liquid phase refrigerant at a high pressure and normal temperature. The liquid refrigerant at the high pressure and normal temperature flows in a refrigerant divider 25 through a liquid duct 23 that divides the refrigerant into two branched flows. One branched flow is expanded and throttled to become a saturated and mist type refrigerant at a low pressure and low temperature to flow through a first duct 251 and a heat exchanger 24 on the first duct to become a subcooling liquid refrigerant at a high pressure and low temperature, then is expanded through an air conditioning expansion valve 253 to become a saturated and mist type liquid and gas refrigerant to enter an evaporator 26 to be vaporized to absorb a great amount of latent heat in the air of an air conditioning room to generate refrigeration. Cooling air is delivered through an air conditioner 27 to the air conditioning room. The refrigerant absorbs heat to become low pressure at the normal temperature, and flows to an ice storage refrigerant loop 28 of an ice storage tank to store ice through residual refrigerant. Another branched flow of the cooling liquid refrigerant flows to a second duct 252 to be expanded through an ice storage expansion valve 254 and delivered to the ice storage refrigerant loop 28 to store the ice. Finally the refrigerant in the ice storage refrigerant loop 28 that has finished the ice storage operation returns to the compressor 21 through the gas duct 29 to complete one refrigerant circulation cycle of an air conditioning system.

In the event that the heat exchange medium of the evaporator 26 is chill water, the returned chill water flowing out of the air conditioner 27 is delivered to a chill water side of the evaporator 26 through a chill water pump to form chill water of a low temperature (generally at 7□) to supply the chill water required in the air conditioner 27 to produce air conditioning, and cool the heat load in the air conditioning room to complete one chill water circulation cycle.

Refer to FIG. 3 for the apparatus of the invention. To facilitate utilization of the condensate of the ice storage air conditioning of the invention, the apparatus includes an outdoor device 30 which contains the compressor 21 and the condenser 22, an indoor device 40 which is connected to the outdoor device 30 through the gas duct 29 and the liquid duct 23. The indoor device 40 includes an ice storage tank 50 to maintain temperature. The ice storage tank 50 has the ice storage refrigerant loop 28 at the upper half portion and the heat exchanger 24 at the lower half portion. The evaporator 26 is located above the ice storage tank 50. The air conditioner 27 is located above the evaporator 26. There is an air outlet 271 of the indoor device 40 on an upper side of the air conditioner 27 to deliver cooling air to the air conditioning room. Below the evaporator 26 there is a condensate collection tray 51 to recycle the low temperature condensate generated during operation of the air conditioning. The collected water of the condensate collection tray 51 is channeled to the ice storage tank 50 to automatically replenish the chill water. Such a design does not require replenishing additional water to the chill water circulation cycle during operation of the air conditioning. Moreover, the low temperature condensate can cool the refrigerant at the outlet of the condenser 22 to become the subcooling liquid refrigerant during ice storing or melting to enhance refrigeration effect.

The refrigerant divider 25 divides the refrigerant according to different conditions of the air conditioning room and distributes the refrigerant to the first duct 251 and the second duct 252 according to the following conditions:

1. No load in the cooling room: Q0=Q2;

2. Low load in the cooling room: Q0=Q1+Q2;

3. Full load in the cooling room: Q0=Q1;

4. High load in the cooling room: Q0=Q1+ice storage cooling energy.

Where Q0 is total refrigerant amount; Q1 is the refrigerant amount in the first duct 251, namely the refrigerant amount flows first to the evaporator 26; Q2 is the refrigerant amount in the second duct 252, namely the refrigerant amount directly flows to the ice storage refrigerant loop 28.

1. During the condition of no load in the cooling room, the refrigerant divider 25 closes the first duct 251 to allow all the refrigerant to directly flow through the second duct 252 to the ice storage refrigerant loop 28 so that all the refrigerant serves to store energy in ice. The stored energy can be used in the condition of high load in the cooling room later.

2. During the condition of low load in the cooling room, a sensor sends a signal of a measured temperature to the refrigerant divider 25 which controls the ratio of the refrigerant amount Q1 in the first duct 251 and the refrigerant amount Q2 in the second duct 252 according to actual requirement so that the refrigerant amount Q1 in the first duct 251 can be changed to feed into the evaporator 26 according to alteration of the room temperature. The rest of the total refrigerant Q0 is distributed to the second duct 252. Referring to FIG. 4 for distribution of a low air-conditioning load and an ice storage refrigeration load in the condition of a low cooling room. The flow amount of the refrigerant is divided into two portions. One portion flows to the evaporator 26 to meet the need of the low load in the cooling room, and other portion directly flows to the ice storage refrigerant loop 28 to generate refrigeration to store ice. The total load of the total refrigerant Q0 can reach 100% full load condition.

3. During the condition of full load in the cooling room, the second duct 252 is closed by the refrigerant divider 25. All the refrigerant goes through a phase change and flows directly to the evaporator 26 through the first duct 251 and is consumed there. Hence all the refrigerant Q0 is used to support the load of the cooling room.

4. During the condition of high load in the cooling room, the refrigerant divider 25 sends all the refrigerant to the evaporator 26, but the temperature detected by the sensor does not yet reach a set temperature, namely the refrigeration power provided by all the refrigerant Q0 is not adequate, the ice storage tank 50 melts the ice through the heat exchanger 24 so that the cooling energy of the stored ice generated by the ice storage refrigerant loop 28 during the conditions of the previous no load in the cooling room and low load in the cooling room is released to provide the energy according to the loading requirement of the cooling room, thereby to enable the cooling room to reach the required temperature. Refer to FIG. 5 for load distribution of a high load cooling room and an ice melting load in the condition of a high cooling room. The refrigerant flow is same as for the condition of the fully loaded cooling room. The refrigerant divider 25 closes the second duct 252, and all the phased changed refrigerant is sent to the evaporator 26 so that the total refrigerant amount Q0 is to meet the loading requirement of the cooling room. At this moment the energy provided by the compressor 21 cannot meet the loading requirement of the high load in the cooling room. The cooling energy of the ice storage generated during the conditions of no load in the cooling room and low load in the cooling room is transformed through the heat exchanger 24 to cool the refrigerant to become the subcooling refrigerant. The temperature of the liquid refrigerant is lowered to increase subcooling of the refrigerant. As a result the circulation amount of the refrigerant can be increased and the cooling capability of can enhanced by about 30%.

Refer to FIG. 6 for a Mollier chart of the invention. It indicates the efficacy analysis of the invention related to the measured pressure and temperature of the main elements, and compares with the conventional ice storage air conditioning system without refrigerant division, where:

h2−h3′=original cooling effect;

h3′−h3=low temperature condensate+enhanced subcooling effect resulting from ice melting; the cooling effect of the invention=(h2−h3′)+(h3′−h3);

h1−h4′=original refrigeration effect;

h4′−h4=the refrigeration effect provided by the subcooling refrigerant;

The refrigeration effect of the invention=(h1−h4′)+(h4′−h4).

As a conclusion, the refrigerant division and heat reclaiming from condensate recycling of the invention allow the refrigerant to fully flow to the ice storage tank to store ice or fully flow to the evaporator to melt the ice to provide air conditioning, or partially enter the ice storage and the evaporator. The system can divide and distribute the refrigerant according to the loading condition of the air conditioning room to transfer energy. It can save energy and achieve an optimum cooling effect for air conditioning at a constant temperature.

While the preferred embodiments of the invention have been set forth for the purpose of disclosure, modifications of the disclosed embodiments of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments which do not depart from the spirit and scope of the invention.