WO2018044250A1

WO2018044250A1 - Refrigeration system with centralised condensation heat removal

Info

Publication number: WO2018044250A1
Application number: PCT/UA2016/000124
Authority: WO
Inventors: Viktor Oleksandrovich LUKIANCHUK; Viktor Dmitrovich SOLOVIOV
Original assignee: Joint Ukrainian-Polish Enterprise In The Form The Of Company With Limited Responsibility "Modern-Expo"
Priority date: 2016-09-05
Filing date: 2016-11-02
Publication date: 2018-03-08
Also published as: UA129551U

Abstract

The invention relates to commercial refrigeration equipment, namely commercial refrigerating facilities with a built-in refrigerating unit equipped with a liquid cooling condenser. A proposed refrigeration system is made with centralised condensation heat removal. For this purpose, the known system comprising at least one refrigerating device (1) with a refrigerant circulation loop and a condenser unit with a compressor and a condenser of the refrigerating device uses, according to the invention, a liquid condenser located in the refrigerating device and coupled to at least one closed liquid condensation heat removal loop comprising a means of heat-transfer agent circulation in a liquid loop and a means of heat-transfer agent refrigeration (3) coupled by a heat-transfer agent circulation pipeline (12). This liquid condenser is designed as a plate heat exchanger capable to pass the refrigerant and the heat-transfer agent simultaneously. The claimed invention allows to reduce heat emissions into a room, where refrigerating devices of the system are located, the level of noise from refrigerating devices, system operating costs, in particular, costs associated with installation, materials for the system, system maintenance, etc., to simplify system maintenance and operational flexibility for the purposes of refrigeration, and to reduce negative impact of the system operation on the environment.

Description

Refrigeration System with Centralised Condensation Heat Removal An invention relates to commercial refrigeration equipment, namely commercial refrigerating facilities with a built-in refrigerating unit equipped with a liquid cooling condenser.

Similar designs of refrigeration systems serving of such purpose are known to the applicant, including the following which are considered the closest prior art.

A standard direct refrigeration system comprising refrigerated displays with a built-in unit requires an air-cooled condenser to be installed on each piece of equipment, which leads to release of heat condensation directly into a store, where the equipment is located, as well as to a relatively high level of noise produced by a condenser fan in the store. There is also a system of centralised refrigerant supply (remote refrigeration supply; Fig. 1 illustrates a similar scheme with freon as a refrigerant, where 1 designates compressor equipment with a condenser, 2 - refrigerating equipment with an evaporator for air cooling in a display case, 3 - solenoid, 4 - thermal expansion valve). In this case, such system requires the compressor equipment with the condenser to be located outside of a room with refrigerating devices, making it necessary to use a copper pipeline for refrigerant circulation under high pressure and high temperature in the refrigerant circulation loop, and causing background noise when the system operates from the compressor, which should be powerful enough to produce and supply vapour from the refrigerant to all refrigerating devices making the system.

The prior art also discloses refrigeration systems, in particular those relating to commercial equipment and using an intermediate heat-transfer agent.

In particular, the refrigeration system with built-in refrigeration supply comprising a refrigerating device (a commercial display case) with a refrigerant circulation loop and an intermediate heat-transfer agent circulation loop, that is used as brine solution. The intermediate heat-transfer agent circulation loop is coupled with inner space of the refrigerating device and a heat exchanger. The intermediate heat-transfer agent circulation loop is used to refrigerate the inner space of the refrigerating device and to reduce defrosting time thereof (Patent JP2001012843 A published on January 19, 2001). Therefore, the known system cannot be factory manufactured in full, so that it would require connection only at the place where it is used, as the centralised refrigerating device and the condenser are located in different rooms and should be connected with a copper pipeline.

The prior art further discloses double-loop refrigeration system with isolated external liquid heat-transfer agent comprising a refrigerating device, a refrigerant circulation loop, a condenser unit with a condenser and a compressor, and a heat-transfer agent circulation loop with a heat exchanger used as an evaporator (Application US2008034760A1 published on February 14, 2008). In this system, intermediate heat-transfer agent circulation loop is designed to accumulate energy, providing high reliability of ice formation and storage, lower costs, and reduction of power consumption compared to the single-phase system. Although this system addresses the issue of uniform power consumption by the refrigerating device during a day, it fails to address the issue of complete factory manufacturing of the whole device as well as environmental pollution when the refrigerant is used, in particular, of such types as R12, R502, R22, R134, R404a, R507 which affect the ozone layer and contribute to the greenhouse effect, and the heat-transfer agent, such as ethylene glycol, known to be toxic for all living organisms and corrosion-active, or such as brine solutions, which are highly corrosive and, when used in high concentrations, are harmful to living organisms, or alcohol solutions, which, when enter wastewater, are harmful to plants and microorganisms. The prior art discloses using environmentally friendly gas propane (R-290) in refrigeration systems, in particular those disclosed by US6268317B1 dd. July 31, 2001, which does not affect the ozone layer of the Earth. However, its use in standard systems, in particular those described above, is impossible because of its relatively high fire danger and the need to increase the size of the condenser.

A refrigeration system comprising at least one refrigerating device with refrigerant circulation loop and a condenser unit with a compressor and a condenser of the refrigerating device (patent UA 105207 published on October 03, 2016) is taken as a prototype. An air condenser is used as the condenser of the refrigerating device. The system further comprises a receiver, a filter drier, a solenoid valve, a thermal expansion valve, an evaporator, a storage tank, a pump, cold utilizer, switching valves, consumers of the refrigeration with valves regulating consumption of the intermediate heat-transfer agent, as well as internal and external temperature sensors. Further, the cold utiliser is located outside the room and is coupled with an external temperature sensor, while an internal temperature sensor is installed on the main line coupling consumers of refrigeration with the cold utiliser and the storage tank. In this system, intermediate heat-transfer agent is used to refrigerate products in a refrigerating chamber rather than to transfer heat to the environment.

The object of the invention is to reduce heat emissions into the room where the refrigerating devices of the system are located, such as a store room, and to reduce noise from refrigerating devices. An additional object requiring comprehensive approach to address this issue is:

— to reduce operating costs of the system given the cost of installation, materials for the system, maintenance etc.;

— to simplify the system maintenance and provide operational flexibility for the purposes of refrigeration; — to reduce negative impact of the system during operation on the environment, in particular the ozone layer, including compliance with the requirements of the Montreal and Kyoto protocols.

This object is achieved when the refrigeration system is made with centralised condensation heat removal. For this purpose, the known system comprising at least one refrigerating device with the refrigerant circulation loop and the condenser unit with the compressor and the condenser of the refrigerating device uses, according to the invention, liquid condenser located in the refrigerating device and coupled to at least one closed liquid condensation heat removal loop comprising a means of heat-transfer agent circulation in a liquid loop and a means of heat-transfer agent refrigeration coupled by a heat- transfer agent circulation pipeline. This liquid condenser is designed as a heat exchanger capable to pass the refrigerant and the heat-transfer agent simultaneously.

According to another embodiment of the invention, a pump is used as a means of heat-transfer agent circulation in the liquid loop.

According to yet another embodiment of the invention, a means of heat- transfer agent air refrigeration is used as the means of heat-transfer agent refrigeration.

In the above embodiment of the invention, a dry cooling tower with variable speed fans is used as the means of heat-transfer agent air refrigeration.

According to yet another embodiment of the invention, the liquid loop for condensation heat removal further comprises an expansion tank, at least one filter, pressure gauges, an automatic air valve, a safety valve, a set of valves, and an electric unit for system protection, management, and control. According to yet another embodiment of the invention, propylene glycol solution or ethylene glycol solution or alcohol solution or brine solution is used as the heat-transfer agent.

In the above embodiment of the invention, a polypropylene pipeline is used as the heat-transfer agent circulation pipeline.

According to yet another embodiment of the invention, gas R-290 (propane) is used as a refrigerant.

According to yet another embodiment of the invention, the heat exchanger may be designed as a plate one.

According to yet another embodiment of the invention, the amount of refrigerant in the refrigerant circulation loop does not exceed 150 g.

The following cause-effect relationship exists between the claimed technical result and the combination of essential features of the invention.

The embodiment of each refrigerating device (e.g., a display case) with the liquid cooled condenser and condensation heat removal from the condenser of each refrigerating device taking place when the refrigerant circulation loop is in operation using the intermediate heat-transfer agent through the closed liquid condensation heat removal loop which joins condensers of all refrigerating devices allows to provide condensation heat removal outside the room where the refrigerating device is located (e.g., a store room). The heat-transfer agent is refrigerated outside the room by passing through the dry cooling tower where the liquid heat-transfer agent is cooled by environmental air, and the cooled heat- transfer agent is removed by the pump and then supplied through a closed loop for re-cooling of condensers of refrigerating devices. Thus, the use of the heat- transfer agent hardly needs its renewal (only in emergency cases, etc.) that minimises operating costs of the refrigeration system and, therefore, simplifies the system maintenance. Such system does not require using an air condenser which is typically used for both built-in and remote refrigeration systems.

Therefore, the claimed technical result is achieved by separating the process of the heat transfer which is removed from the refrigerating device in the claimed system in two stages:

1) refrigeration of the working volume (a display case) of the refrigerating device using circulation of the refrigerant, e.g. propane (R-290), in a small volume circulation loop,

2) transfer of refrigerant condensation heat to the environment outside the room where the equipment is installed using the intermediate heat-transfer agent.

All the above features, except for the main result, also reduce installation costs compared to those associated with the direct refrigeration system (with a remote compressor) as described above, reduce the system installation and operation requirements, improve system energy performance as refrigerant R- 290 (propane) has better thermophysical properties.

Condensation of the refrigerant in each refrigerating device performed using the heat exchanger cooled by the heat-transfer agent circulating through the condensation heat removal loop improves efficiency of refrigerant condensation and, at the same time, condensation heat removal, which simplifies the system and improves its operational flexibility for the purposes of refrigeration. Further, the use of plate heat exchanger increases performance coefficient of heat exchange process and is more appropriate in terms of ease of operation and cost of production.

Further, such system allows to significantly reduce the amount of the refrigerant (no less than 150 g) to refrigerate the inner space of each refrigerating device, leading to a significant reduction of the length of a copper pipeline for the system in general, as the latter is only required for refrigerant circulation in the refrigeration loop and condensation heat is transported by the intermediate heat- transfer agent (e.g., propylene glycol solution) to the remote dry cooling tower not through a copper pipeline, but through, for example, a polypropylene pipeline (any other material meeting the requirements of conventional water supply may also be used for the pipeline), the use of which reduces costs of pipelines, simplifies its installation and reduces operating costs. Thus, in the claimed system, the pipeline is mainly used for circulation of the intermediate heat-transfer agent at a temperature ranging from -20 to +50 °C and under pressure of 0.5 ... 3.5 bar, i.e. according to the parameters meeting liquid supply or circulation requirements in typical water pumping networks, which significantly reduces the requirements to pipeline materials, installation and maintenance and allows to use household pipelines.

Thus, when the claimed system is used, refrigerating devices may be supplied, so that they are full ready for commissioning unlike the systems known in the prior art, which use a copper pipeline for refrigerant circulation between refrigerating devices requiring additional and rather costly installation and maintenance operations.

Thus, centralised condensation heat removal, as described above, in particular, condensation heat removal into the environment through one means of heat-transfer agent refrigeration outside the room allows to use multiple low- noise compressors located in the room instead of one powerful and noisy compressor (according to the single-loop system known in the art as described above), that also reduces background noise, caused by the system operation. It is obvious that one means of heat-transfer agent refrigeration, which refrigerates the same volume of the heat-transfer agent is less noisy than a large set of air condensers embedded in each refrigerating device, especially when there are many refrigerating devices.

During testing the claimed system, the inventors found that the total power consumption was reduced by 10% compared to the known systems, in particular, those with remote refrigeration supply, while overall power consumption was reduced by 25% compared to built-in refrigeration supply systems.

Further, simplification and reduction of operating costs is achieved in that in the event of failure of the one refrigerating device only such unit of the system requires repairs or replacement that does not require to stop operation of the entire system.

Further, using eco-friendly, safe, and energy efficient refrigerant and heat- transfer agent in the system minimises impact on the environment, in particular, the ozone layer.

The claimed invention is illustrated by an exemplary embodiment of the system and its operation, as well as by the drawing where:

1) Fig. 1 shows the refrigeration system with remote refrigeration supply;

2) Fig. 2 shows the general scheme of the claimed refrigeration system with centralised condensation heat removal.

The refrigeration system with centralised condensation heat removal (Fig.

2) comprises at least one refrigerating device 1 with the refrigerant circulation loop located in the refrigerating device 1. The refrigerant circulation loop may comprise a motor-driven compressor, a refrigerant evaporator with a regulating unit (a capillary tube) and a refrigerant circulation pipeline (not shown on Fig. 2). The refrigerant circulation loop is not the subject of this invention. The liquid condenser is located in each refrigerating device 1. The refrigerant evaporator is filled with the refrigerant - gas R-290 (propane). In this case, the volume of the refrigerant in the refrigerant circulation loop may not exceed 150 g.

The refrigerant circulation loop of the refrigerating device 1 comprises the liquid condenser located inside the device 1. The liquid condenser is coupled with at least one closed liquid condensation heat removal loop. The condensation heat removal loop comprises the means of heat-transfer agent circulation 2 in the liquid loop and the means of heat-transfer agent air refrigeration 3 coupled with heat-transfer agent circulation polypropylene pipeline 4. The pump, for example, with a ball valve may be used in the liquid loop as the means of heat-transfer agent circulation 2. The dry cooling tower with variable speed fans may be used as the means of heat-transfer agent air refrigeration 3. The liquid condenser of the refrigerant circulation loop of the refrigerating device 1 is designed as the plate heat exchanger having channels to pass the refrigerant. Heat-transfer agent circulation channels 4 pass through such plate heat exchanger of the refrigerant circulation loop of the device 1. The condensation heat removal loop further comprises the extension tank 5, at least one filter 6, pressure gauges 7, the filling valve 8, the drain valve 9, the safety valve 10, the ball valves 11 and the flexible pipelines for connection thereof 12 and the electric unit for system protection, management, and control 13, the air exhaust valve 14. Liquid having a low freezing point and inert to corrosion may be used as the heat-transfer agent so that its temperature can be lowered to the ambient temperature when the system is operated in winter depending on the climate zone where it is installed. Therefore, the system can use propylene glycol solution or ethylene glycol solution or alcohol solution or brine solution meeting the above requirements as the heat-transfer agent. Propylene glycol, in particular as 25-45% solution, is preferable given its environmental safety and thermophysical characteristics for operation in the required temperature range and corrosion inertness.

The described system is used as follows. When the refrigerating device 1 is in operation, the refrigerant is pumped through the refrigerant circulation loop and the condenser of the refrigerating device 1. Condensation heat is removed by the heat-transfer agent (aqueous propylene glycol solution) in the condenser - plate heat exchanger of the refrigerating device 1 and is supplied by the pump 2 through heat-transfer agent circulation pipeline 4 and expansion tank 5, at least one filter 6, pressure gauges 7, the filling valve 8, the drain valve 9, the safety valve 10, the ball valves 11, flexible pipelines 12 to the dry cooling tower 3, the air exhaust valve 14. In the cooling tower 3, heat coming from the heat-transfer agent is removed by its refrigeration with environmental air using fans of the cooling tower 3. The cooled heat-transfer agent is removed by the pump 2 to further supply to the closed liquid condensation heat removal loop and then back to condensers - plate heat exchangers of each refrigerating device 1 of the refrigeration system.

The extension tank 5 is used to compensate temperature changes in the volume of the heat-transfer agent. The hydraulic filter 6 is used to purify the circulating liquid heat-transfer agent. Pressure gauges 7 are used to control the hydraulic filter 6 for blockage. The safety valve 10 is used to remove fluid in case of emergency overpressure in the system. The exhaust valve 14 is used for deaeration of the heat-transfer agent circulating in the loop. Ball valves 11 and flexible pipelines 12 are used to connect the said system elements or to connect additional elements.

The electric unit for system protection, management, and control 13 is used for power supply to system elements and to obtain and control readings of system elements. The present invention allows to reduce heat emissions into the room, where the refrigerating devices of the system are located, the level of noise from refrigerating devices, system operating costs, in particular, costs associated with installation costs, materials for the system, system maintenance, etc., to simplify system maintenance and operational flexibility for the purposes of refrigeration, and to reduce negative impact of the system operation on the environment.

Claims

1. A refrigeration system with centralised condensation heat removal comprising at least one refrigerating device with the refrigerant circulation loop and the condenser of the refrigerating device, wherein said condenser being a liquid condenser located in the refrigerating device and coupled to at least one closed liquid condensation heat removal loop comprising the means of heat- transfer agent circulation in a liquid loop and the means of heat-transfer agent refrigeration, coupled by the heat-transfer agent circulation pipeline, and said liquid condenser being designed as the heat exchanger capable to pass the refrigerant and the heat-transfer agent simultaneously.

2. The system according to claim 1, wherein a pump is used as said means of heat-transfer agent circulation in a liquid loop.

3. The system according to claim 1, wherein a means of heat-transfer agent air refrigeration is used as said means of heat-transfer agent refrigeration.

4. The system according to claim 3, wherein a dry cooling tower with variable speed fans is used as said means of heat-transfer agent refrigeration.

5. The system according to claim 1, wherein said liquid loop further comprises the extension tank, at least one filter, pressure gauges, the filling valve, the drain valve, the air safety valve, the ball valve, and the air exhaust valve and the electric unit for system protection, management, and control.

6. The system according to claim 1, wherein propylene glycol solution or ethylene glycol solution or alcohol solution or brine solution is used as said heat- transfer agent.

7. The system according to claim 6, wherein a polypropylene pipeline is used as said heat-transfer agent circulation pipeline.

8. The system according to claim 1, wherein gas R-290 (propane) is used as said refrigerant.

9. The system according to claim 1, wherein the heat exchanger is designed as a plate one.

10. The system according to claim 8, wherein the amount of said refrigerant in the refrigerant circulation loop does not exceed 150 g.