Investigation of ammonia/water hybrid absorption/compression heat pumps for heat supply temperatures above 100 °C

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Abstract

The hybrid absorption/compression heat pump (HACHP) using ammonia-water as working fluid is a promising technology for development of a high temperature industrial heat pump. This is due to two properties inherent to the use of zeotropic mixtures: non-isothermal phase change and reduced vapour pressures. Using standard refrigeration components (28 bar) HACHP up to 100 °C are commercially available. Components developed for high pressure NH3 (52 bar) and transcritical CO2 (140 bar) increase the limiting allowable pressures. It is therefore relevant to evaluate the feasible supply temperatures using these components. A technically and economically feasible solution is defined as one that satisfies constraints on the coefficient of performance (COP), low and high pressure, compressor discharge temperature and volumetric heat capacity. The ammonia mass fraction of the rich solution and the liquid circulation ratio both influence these constraints. The paper investigates feasible combinations of these parameters. A numerical HACHP model is developed in Engineering Equation Solver (EES). The constrained parameters are evaluated for a range of combinations for systems with supply temperatures of 100 °C, 125 °C, 150 °C and 175 °C. Results show that standard components are applicable up to 100 °C, equipment for high pressure NH3 up to 125 °C, and equipment for transcritical CO2 up to 175 °C.
Original languageEnglish
Title of host publicationProceedings of the International Sorption Heat Pump Conference (ISHPC 2014)
Number of pages10
Volume1
PublisherCenter for Environmental Energy Engineering
Publication date2014
Pages311-320
ISBN (Print)978-1-63266-596-6
Publication statusPublished - 2014
EventInternational Sorption Heat Pump Conference (ISHPC 2014) - Washington, United States
Duration: 31 Mar 20146 Apr 2014

Conference

ConferenceInternational Sorption Heat Pump Conference (ISHPC 2014)
CountryUnited States
CityWashington
Period31/03/201406/04/2014

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