GB2108261A - Heat pipe assemblies - Google Patents

Abstract

A heat pipe in the form of a conformable thermal conditioning garment (10) to be employed in the removal of heat to a remote heat sink (ABWACS) has a liquid distribution means comprising a perforate tube (24) receiving an end of the heat pipe wick material (21). <IMAGE>

Description

SPECIFICATION Improvements in heat pipes The present invention relates to heat sources-cumsinks, and especially to heat pipes constituted as thermal conditioning clothing for humans.

In UK Patent Specification 8106782 there is described a flat, flexible or conformable heat pipe assembly suitable for use as a thermal conditioning garment, the assembly having a reticulated sstructure including wicking and voic continua, an impermeable plastics film envelope surrounding the structure, and a valve in the envelope by which the assembly may be outgassed and evacuated and liquid introduced thereinto.

According to the present invention a heat receiver element of sheet heat pipe form, that is having an encased reticulated structure including wicking and void continua, and for use in a heat pipe assembly, has liquid distribution means comprising an elongate perforate tube contacting the wicking throughout its perforate length.

The heat pipe assembly may comprise liquid and vapour transfer means connected to the heat receiver element, the liquid transfer means being connected to the liquid distribution means and the vapour transfer means to the voic continua, the transfer means being also connectable to heat sink means. The heat pipe assembly may further comprise heat sink means so connected.

The elongate perforate tube may simply be a tube with discrete perforations throughout its working length and the contact between that and the wicking obtained by wrapping wicking around the tube and/or poking strands thereof through the perforation. Alternatively the perforation may be realised in a slit, and perhaps the wicking edge retained in the split perhaps by tube resilience, or perhaps by thread sewn through the wicking and passing around the tube. Where the attitude of the receiver element is not likely substantially to alter whilst in use, in particular is not likely to be inverted more than momentarily, the perforation of the distribution tube is advantageously sited in a substantially uppermost part thereof. This can assist in preventing parts of the receiver element, particularly lowermost parts, from being swamped and ensuring that the liquid remains with the wicking.Moreover where the receiver element is to be used occupying a substan tiallyvertical plane the liquid distribution means are preferably disposed substantially uppermost therein.

The tube may be endless, eg annular, and is preferably formed of resilient, flexible plastics.

It will be appreciated that the distribution means of the present invention are particularly suitable for use in heat pipe assemblies where the heat sink element is not in heat pipe form but merely supplies cooled liquid, perhaps condensing vapour received from the receiver element to provide the liquid. In such circumstances, where it may be advantageous for geography and weight reasons not to employ wicking in the transfer means, a liquid transfer means wicking interface, such as is the subject of the present invention, will be required. These circumstances can readily prevail in the context of thermal conditioning garments, when separability of a receiver element in garment form and the heat sink can be highly desirable.The usual requirement for substantially a vacuum within the apparatus, and the exclusion of contaminants, may be met on the one hand by the provision of pump means as part of the heat pipe assembly and on the other by suitable isolating valve means in the connector by which elements to the assembly are disconnected. These provisions are described more fully in co-pending UK Patent Applications 8227054-5.

An example of apparatus in accordance with the present invention will now be described with reference to the accompanying drawings, of which: Figure 1 illustrates a thermal conditioning garment, Figure2 is a section at II in Figure 1, and Figure 3 is a section at III in Figure 1.

The thermal conditioning garment shown in Figure lisa poncho style undergarment 10 shaped to overlie the shoulders of a person. It comprises plastics structure 20 supporting a perforated wick sheet 21 and surrounded by a non-rigid, impermeable plastics envelope 22. The structure 20 provides a continuous void hind the wick 21 and coextensive therewith. The garment carries an umbilicai heat transfer lead 23 leading to a connector PEC. The garment is therefore substantially similar in construction to that described in UK Patent Specification 8106782.

The garment is constructed as a heat receiver element, so that the umbilical lead 23 is arranged for the conveyance of cool liquid to aid vapour from the garment. Thus the garment and lead 23 contain liquid distribution means in the form of a flexible plastics tube 24 leading from the lead 23 up one side of the garment, across the shoulders and around the neck of the garment. Across the shoulders, ie in the region II, and across the neck front and back, ie in region Ill, the tube 24 is slit in a substantially uppermost location. Edges 25 of the wick 21 are held in the slits by thread 26 sewn through the wicks and passed around the tube 24.

Figure 1 also illustrates in block form a servicing unit suitable for use with the garment 10. It comprises a liquid pump 31, a motor MPU, a compressor 32, an evacuator 33, an air blower pump 34, and a condenser unit ABWACS with a water reservoir 35. A liquid duct 40 connects the condenser ABWACS with the connector PEC via the pump 31, and a vapour duct 41 connects the condenser with the connector via the compressor 32. From the duct 41 between the condenser and the compressor a duct 42 leads to the evacuator 33, while the blower 34 communicate with the sink via a duct 43.

The motor MPU is arranged for driving the pump 31, the compressor 32, the blower 34 and the evacuator 33 intermittently. The pump 31 is a peristaltic pump to preserve cuting integrity, and serves as a non-return valve to the heat sink ABWACS. The compressor 32 serves partially to condense and to raise the temperature of the vapour to facilitate operation of the heat sink ABWACS, and is more particularly described in copending UK patent application 8129023. The evacuator 32 is employed initially to evacuate the assembly and serves by intermittent operation to maintain a low pressure regime within the assembly. It is particularly described in copending UK patent application 8129028. The air blower 34 and the reservoir 35 associated with the heat sink ABWACS are more particularly described in copending UK patent application 8129027.

The connector PEC includes valves by which the garment 10 is isolatable, so that it can be supplied for use already outgassed and perhaps partially evacuated.

The assembly is prepared for use by being connected as described and shown, when the connector PEC automatically establishes communication between ducts 24 and 40 etc, the poncho donned by someone about to enter a hot environment, and the heat sink ABWACS and the reservoir 35 charged with water. The motor MPU is switched on when the environment to the garment wearer has become hot.

Then the pump 31 pumps water from the sink ABWACS via the ducts 40 and 24 into the garment 10 and the compressor 12, by compressing the vapour it receives from the garment via the duct 41, raises the temperature thereof while passing it to the sink ABWACS. In the sink ABWACS the vapour is condensed and the water so formed cooled. This is principally effected by means of thermal contact over an extensive area between the working fluid and a wick in the sink moistened with water from the reservoir 35 and dried by airflow from the blower 34 and duct 43. The evacuator 33 operates intermittentliy to maintain the evacuated state of the assembly interior.

Within the garment 10, upon reaching stations II and Ill the liquid is absorbed from the tube 24 into the wick 21 and is distributed therethrough. As the liquid isvapourised by heat from the body the vapour is conveyed via the structure 20 and the leads 23 and 41 to the compressor 32.

Garments in accordance with the invention may be worn by personnel working in hot environments, such as military personnel, particularly tank crew and aircrew, and furnace operatives. They may be particularly useful in the aircrew context. for in the event of emergency egress over sea the connector PEC, which may be part of an ejector seat mounted personal equipment connector, may be arranged both to isolate the interior of the garment and to minimise the extent to which it and the lead 23 can act as a heat sink per se.

Claims (12)

1. A heat pipe assembly comprising a heat receiver element of sheet heat pipe form, that is having an encased reticulated structure including wicking and void continua, and having liquid distribution means comprising an elongate perforate tube contacting the wicking throughout its perforate length.

2. A heat pipe assembly as claimed in claim 1 and having liquid and vapour transfer means connected to the heat receiver element, the liquid transfer means being connected to the liquid distribution means and the vapour transfer means to the voic continua, the transfer means being also connectable to heat sink means.

3. A heat pipe assembly as claimed in claim 2 and indicating heat sink means so connected.

4. A heat pipe assembly as claimed in any one of claims 1 to 3 and wherein the wicking protrudes into the perforator.

5. A heat pipe assembly as claimed in any one of claims 1 to 4 and wherein the elongate perforate tube is a tube with discrete perforations throughout its working length.

6. A heat pipe assembly as claimed in any one of claims 1 to 4 and wherein the perforation comprises a slit.

7. A heat pipe assembly as claimed in any one of the preceding claims and wherein the alongate perforate tube is resilient.

8. A heat pipe assembly as claimed in any one of the preceding claims and wherein the wicking is sewn to the tube.

9. A heat pipe assembly as claimed in any one of the preceding claims and wherein the perforation of the distribution tube is sired in a substantially uppermost part thereof.

10. A heat pipe assembly as claimed in any one of the preceding claims and wherein the liquid distribution means are disposed substantially uppermost in the heat receiver element.

11. A heat pipe assembly as claimed in any one of the preceding claims and wherein the liquid distribution means comprise an endless tube.

12. A heat pipe assembly substantially as hereinbefore described with reference to the accompanying drawings.