GB2559658A

GB2559658A - Multi-function heat exchanger and temperature control system

Info

Publication number: GB2559658A
Application number: GB1720529.5A
Authority: GB
Inventors: Reader John
Original assignee: G A H Refrigeration Ltd
Current assignee: G A H Refrigeration Ltd
Priority date: 2016-12-08
Filing date: 2017-12-08
Publication date: 2018-08-15
Also published as: GB201720529D0; GB201620907D0

Abstract

A multi-function heat exchanger comprising a heat exchanger having a primary refrigerant circulation circuit 20 and one or more auxiliary refrigerant circulation circuits 30, 40, each circulation circuit being independently controllable by controller 50 and accommodating a different refrigerant or heat exchange fluid. One of the circulation circuits may be a heating circuit. The heat exchanger may comprise three circuits being a primary circuit for refrigerating a load space 60, a first auxiliary circuit 30 for heating the load space, and a second auxiliary circuit 40 having a single-use refrigerant for refrigerating the load space. The first auxiliary circuit may run from an external hot water heating system 35 and the second auxiliary circuit may release CO2 from a pressurized vessel 45 to provide emergency cooling. A temperature control system using the heat exchanger is also disclosed. The second auxiliary circuit may require a manual trigger to activate.

Description

(71) Applicant(s):

G.A.H (Refrigeration) Limited c/o BDO LLP, 16 The Havens, Ransomes Europark,

Ipswich, Suffolk, IP3 9SJ, United Kingdom (51) INT CL:

F25B 25/00 (2006.01) F25B 39/04 (2006.01) F28D 21/00 (2006.01) (56) Documents Cited:

EP 1134514 A1 US 4344296 A1 KR20140113076 (58) Field of Search:

INT CL F25B, F28D Other: EPODOC, WPI

F25B 39/02 (2006.01) F25B 49/02 (2006.01)

WO 2007/018524 A2 US 20040244396 A1 (72) Inventor(s):

John Reader (74) Agent and/or Address for Service:

Williams Powell

Staple Inn, LONDON, WC1V 7QH, United Kingdom (54) Title of the Invention: Multi-function heat exchanger and temperature control system Abstract Title: Multi-function heat exchanger and temperature control system (57) A multi-function heat exchanger comprising a heat exchanger having a primary refrigerant circulation circuit 20 and one or more auxiliary refrigerant circulation circuits 30, 40, each circulation circuit being independently controllable by controller 50 and accommodating a different refrigerant or heat exchange fluid. One of the circulation circuits may be a heating circuit. The heat exchanger may comprise three circuits being a primary circuit for refrigerating a load space 60, a first auxiliary circuit 30 for heating the load space, and a second auxiliary circuit 40 having a single-use refrigerant for refrigerating the load space. The first auxiliary circuit may run from an external hot water heating system 35 and the second auxiliary circuit may release CO2 from a pressurized vessel 45 to provide emergency cooling. A temperature control system using the heat exchanger is also disclosed. The second auxiliary circuit may require a manual trigger to activate.

1/1

Multi-function heat exchanger and Temperature Control System

Field of the Invention

The present invention relates to a heat exchanger and temperature control system that are particularly applicable for use in refrigeration of vehicle compartments and may also be used for heating.

Background to the Invention

A standard refrigeration system has a condenser and an evaporator. Refrigerant flows around the system in a closed loop with the condenser side normally operating at a high pressure and the evaporator side at low pressure.

An evaporator is an important part of the refrigeration system (and for the avoidance of doubt, air conditioning systems are a type of refrigeration system). It is through the evaporator that a cooling effect is produced in the refrigeration system. Where a refrigeration system is reverse-cycled, it can also be used in heating applications (commonly referred to as a heat pump).

A typical evaporator is formed as a heat pipe or similar, for example from a backand-forth length of copper tubing to which metal fins have been attached. Liquid refrigerant is lowered in pressure and enters the evaporator. As the pressure reduces the refrigerant turns from liquid to gas and absorbs heat by cooling the copper tubing and fins. Heat is removed from the nearby air and causes lowering of the air temperature in the nearby space and results in a cooling effect.

The refrigerant is passed under pressure, typically because it is driven by a compressor, to the condenser which acts generally in the opposite manner to the evaporator, removing heat from the refrigerant and transferring it to the surrounding air. During this process, the temperature of the high pressure refrigerant drops until it condenses into a liquid.

Refrigerant fluids are selected so-as to have properties such that reducing the pressure to which a liquid refrigerant is subjected will cause its temperature to drop sharply. One way this can be accomplished is by passing the liquid through a flowrestrictor such as a specialised valve or a section of small-bore tubing. As the liquid passes from the high-pressure zone to the low-pressure zone through the flow restrictor, its temperature falls and, its circuit complete, is ready to pass through the evaporator again.

One issue with conventional refrigeration systems is that while they work well under predictable conditions and the environment for which they are designed, when conditions or the environment change, they are not necessarily flexible enough to accommodate this and the suitability and/or efficiency of the system reduces.

Statement of Invention

According to an aspect of the present invention, there is provided a heat exchanger having a primary refrigerant circulation circuit and one or more auxiliary refrigerant circulation circuits, each circulation circuit being independently controllable and accommodating a different refrigerant / heat exchange fluid.

Preferably, one or more of the circulation circuits is a heating circuit and one or more of the circulation circuits is a refrigeration circuit. Preferably, the heating and refrigeration circuits have different refrigerant composition selected for optimal performance, respectively, in heating and refrigeration. The circulation circuits may have common refrigerant circulation components such as pumps, compressors etc. and/or may have circulation components individual to the respective circuit.

Preferably, the system includes a controller configured to automatically control operation of at least one of the selected circuits. The controller may make control decisions based on the situation and/or sensor readings and/or other factors.

In embodiments of the present invention, a heat exchanger has a plurality of completely independent circuits, each having a configuration selected primarily for refrigeration and/or heating under predetermined circumstances. In one embodiment, the heat exchanger has three circuits, although it may have 2 or 4 or more depending on the type of application that the system will be put to.

In one embodiment, the heat exchanger has a primary circulation circuit that is operated for primary refrigeration. This is operated in the conventional way when demand and/or environmental conditions are within a predetermined normal envelope. Preferably, this gives full refrigeration duty along with some heating capability when the primary circulation circuit is run in reverse cycle. In this embodiment, the heat exchanger has a first auxiliary circulation circuit that uses a water I glycol mix. In this embodiment, the first auxiliary circuit is run from an external hot water heating system (a diesel or electric heater may be used for heating the water heating system but heat could come from some other source as needed). The first auxiliary circuit is used when outside the normal for more extreme conditions when substantial heating is required and the refrigeration system is un-able to meet the demand. The heat exchanger may optionally include a second auxiliary circulation circuit. In one embodiment, the second auxiliary circulation circuit may act as an emergency backup refrigeration system so that if there is a failure in the primary circulation circuit/refrigeration system. In such an arrangement, a total loss refrigerant is circulated around the second auxiliary circuit in the event of failure of the primary circuit to give an amount of cooling to the load space whilst alternative transport or storage facilities are being found. In one example, the total loss refrigerant may be carbon dioxide stored under pressure as a liquid and released into the second auxiliary circuit as needed. Further details of such an arrangement can be found in co-pending co-assigned UK patent application No. 1604012.3, the content of which is herein incorporated by reference.

Typically, the controller will only ever run one circuit at any one time, although in extreme situations more than one circuit may be operated in parallel. The controller is preferably programmed or otherwise wired or configured to determine which of the circuits should be run to give the best control of temperature based on the ambient conditions and the required temperature set points. Typically, a total loss circuit is reserved for times when the primary circuit has failed for whatever reason and a level of cooling is required as an emergency backup. This may be under the control of the controller but may also or alternatively require manual activation such as opening a valve or similar.

Figure 1 illustrates an embodiment of the present invention by way of example only.

A heat exchangerlO has a primary refrigerant circulation circuit 20, a first auxiliary circulation circuit 30 and a second auxiliary circulation circuit 40 and a controller 50. Each circulation circuit 20, 30, 40 is independently controllable and accommodates a different refrigerant / heat exchange fluid.

The primary refrigerant circulation circuit 20 is a refrigeration circuit for providing refrigeration to the load space 60. Depending on the type of refrigeration, the primary circuit 20 may be operated in a continuous loop via a compressor and condenser as described above. An example refrigerant used in the primary circuit may be (identified by their ASHRAE, American Society of Heating, Refrigerating and Air-Conditioning Engineers, number): R404A, R134a, R407A, R407F, R452A, a combination thereof or some other refrigerant.

The first auxiliary circulation circuit 30 is a heating circuit that uses a water / glycol mix as a heat exchange medium. The first auxiliary circuit is run from an external hot water heating system 35, although it will be appreciated that the heat source need not be external. In the illustrated embodiment, a diesel heater 36 is used for heating the water heating system 35 but heat could come from some other source as needed.

The second auxiliary circulation circuit 40 is a total loss system. A refrigerant (in the illustrated embodiment CO2 stored under pressure as a liquid) is stored in a vessel that is prevented from entering the second auxiliary circulation circuit by a valve

46. When the valve is opened, the refrigerant entered its gaseous phase while it is vented via the second auxiliary circuit and provides refrigeration to the load space

60. As it is vented and the refrigerant is not intended to be captured and returned to the vessel, it is considered a total loss system. Further vessels can be provided in parallel or to be exchanged once the refrigerant in the vessel 45 is spent.

The controller 50 may be implemented in software, hardware, firmware or some combination. It preferably receives inputs from sensors (not shown) on the operation of the circuits and/or on the load space and its environment. It may also receive user inputs to set temperature set points and/or other criteria for switching between circuits. In operation, the controller 50 determines which of the primary, first auxiliary and (optionally) second auxiliary circuits should be operated based on received inputs and any prior user inputs. In one embodiment, the controller is configured to default to the primary circuit 20 being operated, although if sensors report conditions outside the envelope associated with the primary circuit then a determination is made on whether to switch to the first or second auxiliary circuit 30, 40. Switching between circuits may be as straightforward as triggering operation of one and causing another to cease or it may be more involved with opening/closing of valves etc if shared components are used in the various circuits. The controller 50 may include a prediction/feedback model to enable estimation of the time to switch as the effect on the load space typically would not be instantaneous.

Preferably, the controller is substantially automated but it may include a display or other output to advise users of the circuit being operated. As discussed above, a total loss system may require manual operation - should this be the case the controller may optionally include a warning light or similar, to indicate to the user that manual operation of valve or other manual trigger for the total loss system is recommended so that the second auxiliary circuit is used.

It will be appreciated that Figure 1 only shows aspects of the overall refrigeration/heating system and other components may be included in an implementation. Likewise, only a portion of the circulation circuits is shown and these may be open as shown or a closed loop or some other arrangement.

The actual layout of the circuits will depend on factors such as space available, level of heating or refrigeration needed, load space to be cooled/heated and/or the expected use of the load space. For example, they may run in parallel or in some overlapping or twisted together.

It will be appreciated that various embodiments of the present invention have been presented showing a variety of features. For the avoidance of doubt, the features are interchangeable between embodiments. Additionally, the embodiments are not limited to particular feature combinations.

It is to be appreciated that certain components of embodiments of the invention as discussed may be incorporated as code (e.g., a software algorithm or program) residing in firmware and/or on computer useable medium having control logic for enabling execution on a computer system having a computer processor. Such a computer system typically includes memory storage configured to provide output from execution of the code which configures a processor in accordance with the execution. The code can be arranged as firmware or software, and can be organized as a set of modules such as discrete code modules, function calls, procedure calls or objects in an object-oriented programming environment. If implemented using modules, the code can comprise a single module or a plurality of modules that operate in cooperation with one another.

Optional embodiments of the invention can be understood as including the parts, elements and features referred to or indicated herein, individually or collectively, in any or all combinations of two or more of the parts, elements or features, and wherein specific integers are mentioned herein which have known equivalents in the art to which the invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

Although illustrated embodiments of the present invention have been described, it should be understood that various changes, substitutions, and alterations can be made by one of ordinary skill in the art without departing from the present invention which is defined by the recitations in the claims and equivalents thereof.

Claims

1. A heat exchanger having a primary refrigerant circulation circuit and one or more auxiliary refrigerant circulation circuits, each circulation circuit being independently controllable and accommodating a different refrigerant or heat exchange fluid.

2. The heat exchanger of claim 1, wherein one or more of the circulation circuits is a heating circuit and one or more of the circulation circuits is a refrigeration circuit.

3. The heat exchanger of claim 2, wherein the heating and refrigeration circuits have different refrigerant composition selected for optimal performance, respectively, in heating and refrigeration.

4. The heat exchanger of any preceding claim, wherein the circulation circuits share one or more refrigerant circulation components.

5. The heat exchanger of any preceding claim, wherein at least parts of the circulation circuits run in parallel in a load space to be heated or cooled.

6. The heat exchanger of any preceding claim, wherein at least parts of the circulation circuits overlap in a load space to be heated or cooled.

7. The heat exchanger of any preceding claim, wherein at least parts of the circulation circuits are twisted together in a load space to be heated or cooled.

8. The heat exchanger of any preceding claim having three circulation circuits comprising:

a primary circulation circuit configured for predominant use for refrigerating a load space;

a first auxiliary circulation circuit coupleable to an external hot water heating system and being configured for heating the load space;

a second auxiliary circulation circuit having a single use refrigerant for refrigerating the load space.

9. The heat exchanger of claim 8, wherein the first auxiliary circulation circuit accommodates a heat exchange fluid comprising a water / glycol mix.

10. The heat exchanger of claim 8 or 9, wherein the second auxiliary circulation circuit includes a connector for connecting to vessel storing a refrigerant comprising CO2, the second circulation circuit further comprising a valve for controlling passage of the refrigerant from the vessel through the second auxiliary circulation circuit and a vent for venting the refrigerant from the heat exchanger after it has entered its gaseous phase.

11. The heat exchanger of claim 10, wherein the second auxiliary circulation circuit includes a plurality of connectors for connecting to a plurality of refrigerant containing vessels and a plurality of valves each for controlling passage of the refrigerant from each vessel.

12. A temperature control system for a load space comprising a heat exchanger as claimed in any preceding claim and a controller.

13. The temperature control system as claimed in claim 12 when dependent on claim 8, wherein the controller is configured to monitor one or more of: environmental conditions associated with the load space; and demand for heating or cooling of the load space and is configured to operate the primary circulation circuit in a standard mode or in reverse cycle when the monitored environmental conditions and/or demand are determined to be within a predetermined normal envelope.

14. The temperature control system of claim 13, wherein the controller is configured to operate the first auxiliary circuit when the monitored environmental conditions and/or demand are determined to be outside the predetermined normal envelope and it is determined that the primary circulation circuit when reverse cycled is unable to meet predicted heating requirements or the heating demand.

15. The temperature control system as claimed in claim 13 or 14, wherein the controller is configured monitor operation of the primary circulation circuit and to trigger operation of the second auxiliary circuit upon detecting failure of the primary circulation circuit.

16. The temperature control system as claimed in claim 13, 14 or 15, wherein the controller is configured to determine an optimal one or ones of the circulation circuits to give the best control of temperature in the load space based on ambient conditions and one or more predetermined temperature set points and to trigger operation of the determined optimal one or ones of the circulation circuits.

17. The temperature control system as claimed in claim 13, 14, 15 or 16, wherein the controller is substantially automated.

18. The temperature control system as claimed in any of claims 13 to 17, further comprising a display or other output to advise a user of the circulation circuit(s) being operated.

19. The temperature control system as claimed in any of claims 13 to 17 when dependent on claim 8, wherein release of the refrigerant to the second auxiliary circulation circuit is dependent on user approval, the temperature control system further comprising a user alert light and a manual trigger, the controller being configured to trigger the user alert light upon detecting need of the second auxiliary circuit to prompt the user to activate the manual trigger to signify user approval, the refrigerant being released into the second auxiliary circulation circuit upon activation of the manual trigger.

Application No: GB1720529.5