Design and performance investigation of a novel absorption ice-making system using waste heat recovery from flue gases of air to air heat pump

Abstract

Nowadays, different renewable sources and energy storages are attracting world attention due to the major concerns about the excessive emissions and global energy crisis. Hence, this paper studies design and optimal short-term evaluating of a green absorption ice-making system, which comprises of an air to air heat pump (AAHP) and a Stirling engine. Energy-exergy analysis is used for model investigation. In the proposed system, the AAHP is equipped with an inside evaporator fan, an outside condenser fan, an expansion valve, compressor, condenser and an evaporator to supply total cooling demand of large residential buildings during the extremely hot summer days or transient heat waves. In the presented model, the delicate ice crystals can be formed through the AAHP’s refrigeration cycle by blowing the chilled inside air at the lowest temperature of −8.6 °C to a water tank. Expected energy requirement of compressor, evaporator and condenser fans can be supplied either by Stirling engine or by local electricity grid. Meanwhile, a mid-high temperature waste heat is recovered from the exhaust air of the condenser fan in order to drive the Stirling engine for the next hour. A comprehensive analysis is developed as a non-linear programming (NLP) problem to minimize total energy procurement cost over a 24-h time interval taking into account the operational constraints of AAHP and Stirling engine. Simulation results reveal the validity and effectiveness of the proposed ice-harvesting system with zero-CO2 emissions and near-zero energy consumption.