GB1484799A - Stirling cycle heat pump - Google Patents

Abstract

1484799 Stirling cycle heat pumps; heat exchangers K RAETZ 6 March 1975 9370/75 Headings F4H F4K and F4S A heat pump operating on the Stirling cycle comprises a compression chamber formed by a flexible metal bellows 7<SP>1</SP> of welded construction. The expansion chamber is formed by a second bellows 7 or a displacer and the compression and expansion chambers are connected by a regenerator and hot and cold heat exchangers 11<SP>1</SP>, 11. In the form of Fig. 1 the expansion and compression bellows 7, 7<SP>1</SP> are operated at 90 degrees phase displacement by cranks 6 on a drive shaft mounted in bearings 5. Connecting rods 8 from 90 degrees displaced cranks cause cross-beams 28, 28<SP>1</SP> to reciprocate on guides 4. The lower bellows is the hot end, compressed, heated gas being passed upwards through regenerator 9 and heat exchangers 11<SP>1</SP>, 11, which take off heat and cold respectively. To reduce the dead space in the bellows each has a metal displacer 29, 29<SP>1</SP> covered with plastic to protect the bellows. The cold end bellows 7 is surrounded by a telescopic housing carrying a regenerator 17 so that air expelled from between the folds of the bellows during compression gives up heat to the regenerator, the heat being taken up again by re-entering air during expansion. Gas passing from one bellows to the other passes through hot heat exchanger 11<SP>1</SP>, the regenerator 9, which is divided into two parts one on each side of the drive shaft, and cold heat exchanger 11. The whole apparatus may be enclosed in a pressure vessel, the pressure serving to balance the pressure in the bellows and allowing a greater amount of working gas to be used, thereby obtaining a greater output. In the form of Fig. 2 the expansion bellows is replaced by a displacer 23 operated from a second crank or a earn by a driving rod passing through the bellows 21 and sealed at 18. The gas passing between the bellows and the space over the displacer passes through heat exchanger 24, regenerator 22 and a second heat exchanger 24. The heat exchangers may be of the cross-flow type, Fig. 4, water channels 27 being formed through each of a series of elements 12, the working gas passing to and fro through channels 26 formed by spacers 13 between elements. An annular form of this heat exchanger is described (Fig. 5, not shown) suitable for the heat pump of Fig. 2. The gas passes through radial passages and the water through circular passages. The regenerators (Fig. 3, not shown) consist of a roll of corrugated metal foil interleaved with smooth metal foil to form interstices through which the gas passes.