Techno-enviro-exergo-economic evaluation of hot water production by waste heat recovery using U-shaped pulsating heat pipe – an experimental study

Abstract

ABSTRACT The energy crisis and increasing energy demand have prompted scientists and engineers to find ways to recover energy from waste heat. Also, environmental pollution caused by fossil fuels and planning to reduce environmental effects are other reasons for using wasted heat. Many studies have used pulsating heat pipes to transfer thermal energy from high-temperature systems to low-temperature applications and the energy and exergy efficiency of those systems have been investigated, but economic and environmental studies about them have not provided. In this study, the performance of a pulsating heat pipe on the waste heat recovery of a chimney for heating water for household consumption was experimentally investigated. The distilled water with a filling ratio of 60% was considered as the working fluid, and the results are presented for different pulsating heat pipe angles to the horizon from 0 to 90 degrees. Energy and energy analysis and economic and environmental assessments of the waste heat recovery system are presented and discussed. The highest hot water temperature in the reservoir outlet was about 58°C. Also, the CO2 mitigation and cost per cubic meter of hot water generation of the waste heat recovery system were 84.82 tons and 0.1$/m3. Moreover, the efficiency varied from 19% to 54% for horizontal and vertical pulsating heat pipes, respectively.