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A review is presented on the technology, thermodynamics, applications and economics of absorption cycles such as refrigeration, heat pumps and temperature amplifiers; single and multistage cycles, and systems into which they are integrated such asCHP. From this present situation the fundamental thermodynamics of ideal absorption refrigeration is established for single, double and multistage cycles. An exergy analysis is used to prove this theory. The ideal absorption cycle theory is developed to cover absorption heat pumps, cooling with heat recovery, temperature amplifiers and hybrid systems incorporating vapour compression and absorption machines. Having proved absorption cycles to be comprised of Carnot cycles (direct and reverse), this theory was then merged with Carnot driving and cooling cycles' theory to establish a universal law of cold generation cycles. These are combinations of driving and cooling cycles for which the main pmpose is to produce cooling from a combustion driven cycle. The applications and economic evaluations of real direct fired absorption chillers, cold generation systems and the application of absorption chillers to combined heat and power (CHP) systems are analysed. Direct fired chillers have been proved to be economically feasible. The analysis of cold generation cycles indicated the feasibility of certain plant configurations. For the CHP analysis, the exergy costing method was seen to be the most appropriate one for determining the most cost effective application. A review of thermoeconomics applied to an air conditioning system with absorption and CHP is presented. Thermoeconomics was shown to be an appropriate method for optimising systems where absorption cycles are applied. Finally theoretical, practical and economic conclusions are presented regarding the equivalence of vapour compression and absorption cycles.

It is clear that there is no long-term solution to energy supply problems other than planned and continuous conservation. The use of low-grade energy as an unlimited resource will play an important part in maintaining the balance between the future of the world for both developed and developing countries alike. A literature survey reviewing the most promising approaches to the construction of low-grade energy engines has been conducted. The validity of each feasible system has been examined and the principles of operation described. A feasibility study concerning the adoption_of the organic Rankine cycle utilizing common suitable refrigerants (e.g. halo-carbons) as working fluids has been conducted. In particular, the use of a multiple vane expander as the prime mover has been fully investigated. A suite of computer programs has been developed to: • describe working fluid properties; • optimise the geometrical and dynamical parameters of the Rankine cycle to achieve the most efficient operation in both steady and transient states; • optimise the mechanical design of the expander depending upon the mode of operation and the source and sink characteristics. A fully flexible experimental test facility was constructed so as to be capable of testing a wide variety of prime movers. This has been operated for a real time test period in excess of 300 hours. The test results are encouraging. Efficiencies were measured in accordance with the mathematical predictions and a portfolio of suggested modifications towards a high efficiency, low-cost, robust and reliable expander capable of utilising low grade thermal energy has been produced. Fruitful links with relevant British industries have been forged. Demonstrations of the system are planned within the UK and overseas.

The performance of regenerative miniature refrigerators is governed by heat transfer and pressure drop losses, particularly in the regenerator. Steady flow experiments have been performed on various regenerator matrices at cryogenic temperatures and heat transfer from helium gas to the matrix, and pressure drop across the matrix have been determined. These data have been found to be in reasonable agreement with data obtained by other workers using transient flow techniques. In order to determine the applicability of such data to the performance of a cooling engine, experimental methods have been developed to measure the performance and losses in a working Stirling-cycle miniature refrigerator. These techniques have led to the analysis of pressure drop and shuttle heat transfer losses, regenerator efficiency, and to the measurement of other losses in the refrigerator. An energy balance is performed on the machine. These novel techniques, which allow the factors determining poor performance of a working refrigerator to be measured in situ, may be applied profitably to other cyclic machines.