Multisalt-Carbon Portable Resorption Heat Pump

Abstract

Resorption systems are considered as an alternative to vapor compression systems in space cooling, industry and the building sector to satisfy the cooling demand without increasing the electricity consumption [1–3]. Conventional (compression, absorption) heat pumps are not able to function at the waste heat at the temperature level below 200 °C and they can’t provide the temperature lifts 100-150 °C. A large variety of chemical heat pumps exist, but a few resorption chemical heat pumps are available in the literature. Resorption heat pumps provide high storage capacity and high heat of reaction as compared to sensible heat generated by absorption. They ensure the cold and hot output (heating and cooling) simultaneously. Nowadays the sorption technology is steadily improving and the increase at sorption market is strongly related to the energy policy in different countries. Actual sorption technologies (liquid and solid sorption cycles) have different advantages and drawbacks with regard of their compactness, complexity, cost, the range of working temperature [2,4,5]. The resorption technology advantages at first are related to the nature friendly refrigerants such as water, ammonia, CO2 (no CFC, HCFC, HFC) and at second they are thermally driven and can be coupled with a low temperature waste heat, solar heat, burning fossil fuel, or biomass. The unique advantage of resorption systems related with its ability to use a significant number of couples solid-gas [5] without liquid phase and ensure the heat and cold production. The solid resorption machine demonstrated its possibility to be very effective thermal compressor capable to reach the compression ratio more than 100 in one single cycle, which is impossible to have with a single stage vapor compression mechanical device. The optimisation of the sorption technologies is related with multi cascading cycles [2]. From previous publication [5,6], it has been concluded, that chemical heat pumps and refrigerators based on reversible solid-gas resorption cycles could have interesting applications for space cooling, when a high temperature waste heat source is available and/or the exigencies of the harsh external environment necessitates thermal control of an object. The vibration free operation and the large number of solid-gas alternatives make it possible to provide cooling and heating output in the temperature range 243K-573K [6]. The goal of this work is an experimental verification of a basic possibility to advance two-effect sorption cycles using physical adsorption (active carbon fiber, or fabric “Busofit”) and chemical reactions of salts (NiCl2, MnCl2 , BaCl2) in the same machine at the same time interval [5–6] to double the high heat of chemical reaction and sensible heat of physical adsorption to provide high storage capacity, increase the COP and ensure the temperature lift more 100 °C between cold and hot output. Such device can be considered simultaneously as a refrigerator and steam generator, based on the low temperature waste heat application. Usually the heat pump performance can be characterised by the upgrading temperature, specific power production (cooling, or heating), coefficient of performance (COP), coefficient of amplification (COA) and exergetic efficiency. Actual temperature upgrade gives the temperature gain obtained from lower temperature (water) to the high level (steam), while the specific power production gives the amount of heat generated or extracted by the resorption heat pump to the amount of working substance used (“Busofit” + salts). Coefficient of performance COP is defined as the efficiency in cold production (enthalpy of resorption devided by heat supplied for regeneration), while coefficient of amplification COA represents the ratio of hot production to the quantity supplied for regeneration: COP = Qres/Qreg ; COA = (Qres + Qabs)/Qreg.