Heat Pump

Abstract

A heat pump device in which a temperature difference is established between two heat exchangers by inducing cyclical expansion and compression pulses in a working fluid vapour or gas which passes through an adsorbent porous solid located between the heat exchangers.

1 . A heat pump device comprising:
 at least one heat exchanger;   a body of porous absorbent material housing an inlet and an outlet the body being disposed in thermal contact with the heat exchanger, means for passing a working fluid through the body, and   means for inducing cyclical compression and expansion pulses in the working fluid, to cause the working fluid to flow from the inlet to the outlet to create a temperature gradient in the body between the inlet and outlet.   
   
   
       2 . A device as claimed in  claim 1 , further including a heat transfer fluid, means for passing the heat transfer fluid in thermal contact with the heat exchanger, arranged so that the flow of heat transfer fluid removes or adds heat from or to the heat exchanger. 
   
   
       3 . A device as claimed in  claim 2 , wherein the direction of flow of the heat transfer fluid changes with the compression and expansion pulses of the working fluid. 
   
   
       4 . A device as claimed in  claim 3 , wherein the direction of flow of the heat transfer fluid reverses in concert with the compression and expansion pulses of the working fluid. 
   
   
       5 . A device as claimed in  claim 4 , wherein the reversal of direction of flow of the heat transfer fluid is synchronized with said pulses. 
   
   
       6 . A device as claimed in  claim 3 , wherein the frequency of the cyclical motion of the working fluid is the same as the frequency of cyclical motion of the heat transfer fluid. 
   
   
       7 . A device as claimed in  claim 1 , wherein the means for inducing pulses in the working fluid is a positive displacement compressor. 
   
   
       8 . A device as claimed in  claim 1 , wherein the means for inducing pulses in the working fluid comprises a valve switching system and a compressor. 
   
   
       9 . A device as claimed in  claim 8 , wherein the valve switching system alternatively connects the body of absorbent material to high and low pressure reservoirs of the working fluid. 
   
   
       10 . A device as claimed in  claim 1  comprising a further heat exchanger adapted to remove heat of compression from the working fluid before contacting the absorbent material. 
   
   
       11 . A device as claimed in  claim 1 , wherein the temperature gradient comprises a relatively high temperature at the inlet and a relatively low temperature at the outlet. 
   
   
       12 . A device as claimed in  claim 1 , wherein the working fluid is selected from the group consisting of a vapour or gas or a mixture thereof. 
   
   
       13 . A device as claimed in  claim 1  comprising a plurality of heat exchangers. 
   
   
       14 . A device as claimed in  claim 1  in which the working fluid is a single fluorocarbon or a mixture of fluorocarbons boiling between −140° C. and 40° C. 
   
   
       15 . A device as claimed in  claim 14 , wherein the working fluid has a boiling point between −90° C. and 0° C. 
   
   
       16 . A device as claimed in  claim 15 , wherein the working fluid has a boiling point between −90° C. and −20° C. 
   
   
       17 . A device as claimed in  claim 1  in which the working fluid is a hydrocarbon selected from the group consisting of methane, ethane, propane, iso-butane and butane, and mixtures thereof. 
   
   
       18 . A device as claimed in  claim 1  in which the working fluid is nitrogen. 
   
   
       19 . A device as claimed in  claim 1  in which the working fluid is carbon dioxide. 
   
   
       20 . A device as claimed in  claim 1  in which the working fluid is hydrogen. 
   
   
       21 . A device as claimed in  claim 1  in which the working fluid is a noble gas. 
   
   
       22 . A device as claimed in  claim 1  in which the porous solid has at least 10% of its void volume in the form of micropores with diameters less than 2 nm. 
   
   
       23 . A device as claimed in  claim 22  in which the porous solid has at least 10% of its void volume in the form of mesopores with diameters less than 50 nm. 
   
   
       24 . A device as claimed in  claims 23  in which the porous solid has less than 20% of its void volume in the form of macropores with diameters greater than 50 nm. 
   
   
       25 . A device as claimed in  claim 1  in which the adsorbent porous solid is a carbon-based material. 
   
   
       26 . A device as claimed in  claim 25  in which the adsorbent porous solid is a charcoal material. 
   
   
       27 . A device as claimed in  claim 26  in which the adsorbent porous solid is an activated carbon material. 
   
   
       28 . A device as claimed in  claim 25  in which the adsorbent porous solid is an organic polymer-based material. 
   
   
       29 . A device as claimed in  claim 25  in which the adsorbent porous solid is an essentially inorganic material. 
   
   
       30 . A device as claimed in  claim 29  in which the adsorbent porous solid is the oxide of a metal or metalloid element, or combination thereof. 
   
   
       31 . A device as claimed in  claim 29  in which the adsorbent porous solid is a zeolite. 
   
   
       32 . A device as claimed in  claim 29  in which the adsorbent porous solid is a sieve. 
   
   
       33 . A device as claimed in  claim 29  in which the adsorbent porous solid is selected from the group consisting of silica, alumina, titanium dioxide and mixtures thereof. 
   
   
       34 . A device as claimed in  claim 1  in which the adsorbent porous solid is an aerogel. 
   
   
       35 . A device as claimed in  claim 1  in which the adsorbent porous solid is impregnated with a low volatility solvent. 
   
   
       36 . A device as claimed in  claim 1  in which the adsorbent porous solid includes an additive to enhance thermal conductivity. 
   
   
       37 . A device as claimed in  claim 1  in which the enthalpies of adsorption and desorption in the heat exchanger are essentially the same. 
   
   
       38 . A device as claimed  claim 1  wherein said pulses have duration in the range of 1 second to 10 minutes. 
   
   
       39 . A device as claimed in  claim 36 , wherein the duration is in the range of 1 second to 30 seconds. 
   
   
       40 . A device as claimed in  claim 39 , wherein the duration is in the range of 1 second to 10 seconds. 
   
   
       41 . A device as claimed in  claim 1  wherein there is a pressure gradient of working fluid between the inlet and outlet. 
   
   
       42 . A device as claimed in  claim 1  wherein the working fluid is a mixture. 
   
   
       43 . A device as claimed in  claim 42 , wherein the working fluid is a mixture of a strongly adsorbed fluid and weakly adsorbed fluid. 
   
   
       44 . A device as claimed in  claim 42  wherein the working fluid is a mixture of carbon dioxide and nitrogen. 
   
   
       45 . A device as claimed in  claim 42  wherein the working fluid is a mixture of carbon dioxide and argon. 
   
   
       46 . A device as claimed in  claim 42  wherein the working fluid is a mixture of carbon dioxide or ammonia and hydrogen, helium or a mixture thereof. 
   
   
       47 . A device as claimed in  claim 42  wherein the working fluid is a mixture of carbon dioxide and propane. 
   
   
       48 . A heat pump device in which a temperature difference is established between two heat exchangers by inducing cyclical expansion and compression pulses in a working fluid vapour or gas which passes through an adsorbent porous solid located between the heat exchangers. 
   
   
       49 . A device as claimed in  claim 39  in which the temperature difference between each heat exchanger and an external, single-phase, heat transfer liquid is essentially constant.