GB2032085A

GB2032085A - Heat reclamation in refrigeration system

Info

Publication number: GB2032085A
Application number: GB7932511A
Authority: GB
Original assignee: WRIGHT AIR CONDITIONING Ltd
Current assignee: WRIGHT AIR CONDITIONING Ltd
Priority date: 1978-09-22
Filing date: 1979-09-19
Publication date: 1980-04-30
Also published as: GB2032085B

Abstract

A heat exchange system incorporating a compression refrigeration system has a primary condenser 6 and one or more secondary condensers disposed in one or more spaces to be heated, and means associated with the secondary condenser(s) to enhance heat dissipation therefrom into said one or more spaces. Said means may (e.g. as shown) comprise a variable speed blower such as 10A, 10B, 10C, 10D, associated with each condenser such that no heat is extracted from the condenser when the blower is switched off. Alternatively the or each secondary condenser may have heat dissipating fins thereon and a valve adapted to partially or totally by-pass the refrigerant flow through the condenser, said valve being controlled by a thermostat in said space. A blower 6A associated with the primary condenser may be controlled in dependence upon the degree of condensation effected in the secondary condensers. <IMAGE>

Description

SPECIFICATION Heat reclamation in refrigeration system This invention relates to a heat exchange system including a gas compression refrigeration system in which liquid refrigerant is evaporated in an evaporator and, after compression, condensed in a condenser.

In the usual conventional forms of gas compression refrigeration systems, heat is given off at the condenser and is usually wasted. An object of the invention is to provide a heat exchange system in which at least a part of the heat resulting from the refrigeration process is reclaimed for space heating purposes.

According to the invention, a heat exchange system comprises a gas compression refrigeration system having an evaporator, a primary condenser, a separate secondary condenser, and a compressor operable to draw refrigerant vapour from the evaporator and feed it to the condensers, and further comprises means associated with the secondary condenser and acting to enhance heat dissipation from the latter into a space to be heated.

In one convenient arrangement, said means is a blower arranged to blow air over the secondary condenser.

The invention will now be described, by way of example, with reference to the single accompanying drawing which is a diagrammatic representation of one form of the heat exchange system of the invention.

Referring to the drawing, this shows a heat exchange system including a gas compression refrigeration system having a compressor 1 connected by a suction line 2 to an evaporator coil 3 having an expansion valve 3B and being connected by a line 4 and via a liquid receiver 5 to a primary condenser 6. The condenser is connected back to the compressor via a shut-off valve 6A and a conventional compressor discharge valve 6B.

A secondary flow path 7, incorporating isolating valves 7A, 7B, is provided to supply refrigerant to a group of secondary condensers 8A, 8B, 8C, 8D connected together in parallel.

Each secondary condenser is provided with its own respective shut-off valve 8a, 8b, 8c, 8d and the flow path 7 includes a further shut-off valve 9 downstream of the secondary condensers. The secondary condensers 8A to 8D would normally be located, in use, in a space to be heated, or individually or in desired combinations in a plurality of spaces to be heated, and means are provided, shown as respective blowers 1 OA to 1 OD for encouraging heat dissipation from the secondary condensers. The degree of heat dissipation can be governed by controlling the speed of the blowers, or by placing them under the control of thermostatic means located within the or each space being heated.

When it is desired to use the system of the invention as a conventional compression refrigeration system, with no space heating effect, isolating valves 7A, and 7B are closed and valve 6A is opened. Liquid refrigerant absorbs heat by evaporating in the evaporator coil 3 and refrigerant vapour is drawn from the evaporator by the compressor along the linei and pumped to the condenser 6 where the heated vapour gives up heat in condensing back to a liquid. When space heating is required, the valves 7A and 7B are opened and valves 6A and 9 are closed. It will be seen that this permits the hot refrigerant vapour which would normally go directly to the condenser 6 to go via the path 7 and through those of the secondary condensers 8A to 8D of which the cutoff valves 8a to 8d are open.If the blowers 1 OA to 1 OD are all switched off, substantially no heat will be extracted from the secondary condensers and the hot vapour will be returned to the main condenser 6 where normal condensing will occur.

If however, one or more of the blowers 1 OA to 1 OD is switched on, this will cause the vapour in the associated secondary condenser to condense and the liquid refrigerant so formed will return along the path 7 to the main condenser. A blower 6A aids the condensing action of the primary condenser 6 and this may conveniently be responsive to the head pressure produced by the compressor. The system is designed so that if all of the secondary condensers 8A to 8D are operative, then all of the refrigerant passing along the path 7 will be condensed and the pressure switch controlling the blower 6A is arranged to respond to the relatively low pressure head resulting from the use of the secondary condensers in order to switch off the blower 6A.If only three or less of the secondary condensers are in operation, some residual vapour is likely to arrive at the condenser 6 for condensation and the sensitivity of the pressure switch controlling the blower 6A is such that the rather higher pressure head resulting from the use of a reduced number of secondary condensers will switch on the blower 6A, possibly to run at reduced speed. The liquid receiver 5 is of such a size as to contain all the liquid required for operation of the system.

The blowers for the secondary condensers are of the variable speed type so that their operation may be controlled to adapt to the environment in which the secondary condensers are placed. The speeds of the blowers are conveniently controlled so that when the maximum amount of heat is being removed from the secondary condensers, no condensing is being done in the primary condenser 6, the blower 6A of which is switched off by the means described above.

In an alternative embodiment of the system of the invention, heat dissipation from the or each secondary condenser may be effected simply by the provision of fins or the like thereon and control of the heat dissipation may be obtained by using a suitable valve, such a magnetic or solenoid valve, to partially or totally by-pass the flow of refrigerant normally flowing through the secondary condenser. The or each by-pass valve may conveniently be controlled by a thermostat disposed in the space to be heated.

A significant advantage of the system of the invention over some conventional systems using condensers for space heating is that heat is transferred directly by the system refrigerant and no secondary heat transfer medium is required.

The system of the invention is therefore more efficient than those using a secondary fluid. Since the secondary condensers may be disposed in the space or spaces to be heated, the use of air ducting and consequently the power of the secondary condenser blowers are minimised. The installation of the relatively small refrigerant pipe leading to the secondary condensers can be effected without major building work. The refrigerant constituting the heat transfer medium is moved by means of the refrigeration compressor and this system requires no extra pumps for this purpose. The balancing valves and solenoid controlled valves normally incorporated in such systems are dispensed with, whereby the reliability of the system is increased, as compared with conventional systems.

Claims

1. A heat exchange system comprises a gas compression refrigeration system having an evaporator, a primary condenser, a separate secondary condenser and a compressor operable to draw refrigerant vapour from the evaporator and feed it to the condensers and further comprises means associated with the secondary condenser and acting to enhance heat dissipation from the latter into a space to be heated.

2. A heat exchange system according to Claim 1 having a plurality of secondary condensers arranged in parallel with each other.

3. A heat exchange system according to Claim 1 or Claim 2 wherein said heat dissipation means is a blower arranged to blow air over the or each i secondary condenser.

4. A heat exchange system according to any one of Claims 1 to 3 wherein means are provided for selectively isolating the or each secondary condenser from the flow of refrigerant vapour.

5. A heat exchange system according to any one of the preceding claims wherein the primary condenser is provided with a blower for increasing heat dissipation therefrom, this blower being under the control of a pressure switch sensitive to the liquid pressure head of the system, whereby the blower is operated at a reduced rate or rendered inoperative according to the degree of condensation effected by the secondary condenser or condensers.

6. A heat exchange system according to any one of the preceding claims wherein a liquid receiver is interposed between the primary condenser and the evaporater.

7. A heat exchange system substantially as hereinbefore described with reference to the accompanying drawings.