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Double-lift ammonia/water compression-resorption heat pump for simultaneous industrial process heating and refrigeration applications.

Number: 2594

Author(s) : AYOU D. S., CORONAS A.

Summary

The hybridization of absorption and compression heat pump cycles is a promising way to increase the temperature lift and heat sink temperature of industrial heat pumps with acceptable performance. This paper presents a novel double-lift ammonia/water compression-resorption heat pump (DL-CRHP) cycle for the process heating and refrigeration applications in the food and beverages processing industry. The DL-CRHP allows the integration of industrial refrigeration operation, as a heat source, into process heat production at high temperature using a single heat pump with a reduced capital cost and minimal loss of exergy than the separate provision of process heating and refrigeration. The DL-CRHP cycle consists of an evaporator-condenser loop for refrigeration <15 °C and a resorption cycle solution loop, which comprises an absorber and a desorber, for process heat supply at high-temperature level (≥100 °C). The dry R717 vapor compression is carried out in two stages due to the required large-temperature-lift of simultaneous process heating and refrigeration applications in the food and beverages industry, and technical constraints of market-available R717 compressor technologies. The DL-CRHP performance is improved by using refrigerant and solution internal heat recuperators. The present study aims to evaluate the performance of this heat pump cycle by using a simulation model developed under steady-state conditions. At the heat pump cycle design condition, the refrigeration capacity of the evaporator is set to 500 kW with a chilled fluid (ethylene glycol/water mixture) supply temperature between −10 °C and 10 °C, and the temperature glides in the heat sink (hot water) and source (chilled fluid) are 30 K and 10 K, respectively. The effect of hot water and chilled fluid supply temperatures on the heat pump's energetic and exergetic performances was investigated to identify the working domain of the proposed heat pump under imposed component's technical constraints. Simulation results show that the combined heating and refrigeration COP of about 2.02–4.04 and exergy efficiency of 0.467– 0.483 was attainable with a heat sink outlet temperature of 100–150 °C and refrigeration effect at a temperature between −10 °C and 10 °C. The use of a vapor-liquid (internal) heat exchanger allows for reducing the high-pressure compression stage discharge temperature below the current limit of R717 compressor technologies (≤190 °C) in most operating conditions. The development of this type of heat pump, characterized by large-temperature-lift and high heat sink temperature, plays a significant role in the decarbonization of the food and beverage industry, and other industrial applications need simultaneous heating and refrigeration.

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  • Original title: Double-lift ammonia/water compression-resorption heat pump for simultaneous industrial process heating and refrigeration applications.
  • Record ID : 30030787
  • Languages: English
  • Subject: Technology
  • Source: 2022 Purdue Conferences. 19th International Refrigeration and Air-Conditioning Conference at Purdue.
  • Publication date: 2022

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