Thermo-Economic Analysis of Innovative Integrated Power Cycles for Low-Temperature Heat Sources Based on Heat Transformer

Abstract

This paper proposes two novel integrated power cycles as appropriate systems for low-temperature heat sources. The proposed cycles encompass an absorption heat transformer (AHT) system to convert low-temperature heat source to high-temperature source and supply the required heat for driving Kalina cycle (KC) and absorption power cycle (APC) as bottoming cycles. A comprehensive simulation of the system is presented based on the thermo-economic viewpoint. The results show that the AHT/KC has higher energy and exergy efficiencies than the AHT/APC, with 7.69% and 49.03%, respectively. In addition, the sum unit cost of the product (SUCP) for the system is calculated 87.72 $/GJ. According to the results, throttle valve 1 and absorber 1 are the most destructive components of the AHT/KC and AHT/APC, respectively. The net output power in the AHT/KC and the AHT/APC is assessed 60.06 kW and 34.86 kW, respectively. The circulation rate (CR), Coefficient of performance (COP), and exergetic coefficient of performance (ECOP) for both cycles are 3.819, 0.4108, and 0.6107, respectively. The study of key parameters demonstrates that the energetic performance of the proposed power cycles increases and decreases by a rise in the temperature of the generator and condenser, respectively. From the exergetic perspective, rising temperature of the generator improves the efficiency of the cycles, while increasing the ammonia concentration as well as condenser and absorber temperatures reduce the exergy efficiency.