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

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.

KEYWORDS:

• Waste heat recovery
• heat pipe
• pulsating heat pipe
• economic assessment
• environmental assessment

Nomenclature

AMC	=	Annual maintenance price ($)
CPH	=	Cost per cubic meter of hot water ($)
ASV	=	Annual salvage amount ($)
CRF	=	Capital recovery coefficient
FAC	=	First annual cost ($)
UAP	=	Uniform annual cost ($)
ZCO2	=	Enviroeconomic parameter ($)
zCO2	=	Carbon price ($)
Ein	=	Embodied energy (kWh)
HW	=	Annual hot water generation, (m3/year)
${\dot{}\mathrm{Q}}_{\mathrm{w}}$	=	Thermal energy of hot water, W
${\dot{}\mathrm{Q}}_{\mathrm{a}}$	=	Waste heat energy of the chimney, W
Ti	=	Inlet temperature, oC
To	=	Outlet temperature, oC
${\phi }_{\mathit{CO}2}$	=	Environmental parameter (ton $\mathbf{c}{\mathbf{o}}_2$)
	=	Subscripts
w	=	Water
a	=	Air
en	=	Energy

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contribution

Shahin Shoeibi: Conceptualization, investigation, data curation, writing original draft, formal analysis, writing-review, and editing.

Hadi Kargarsharifabad: Conceptualization, performing experiments, formal analysis, writing-review, and editing.

Mehdi Khiadani: Conceptualization, resources, writing-review, and editing.

Mohammad Mehdi Rashidi: Conceptualization, resources, writing-review, and editing.

Additional information

Notes on contributors

Shahin Shoeibi

Dr. Shahin Shoeibi received the Ph.D. degree in mechanical engineering from Islamic azad university, Iran, in 2019. He is expert in the field of energy conversion, especially solar energy applications.

Hadi Kargarsharifabad

Dr. Hadi Kargarsharifabad received the Ph.D. degree in mechanical engineering from Science and research Branch, Tehran, Iran, in 2013. His research interests include experimental, analytical and numerical in heat transfer and fluid flow. He is currently an Associate Professor in the Production and recycling of materials and energy research center, Qom Branch, Islamic Azad University, Qom, Iran.

Mehdi Khiadani

Dr. Mehdi Khiadani I am a A/Professor in the School of Engineering at Edith Cowan University (ECU) in Western Australia with several years of experience in the academic and consulting professions both in Australia and overseas. My industry and research contributions include environmental fluid mechanics and hydraulic engineering.

Mohammad Mehdi Rashidi

Mohammad Mehdi Rashidi Research interests: Heat and Mass Transfer; Multiphase Flows; Micro Fluidics; Computational Fluid Dynamics; Drug Delivery. Highly Cited Researcher for 2018, 2019 and 2020. He has published over 300 journal papers indexed in Scopus and Web of Science Honorary Fellow of the Australian Institute of High Energetic Materials, His papers are published in Nature, Nano Energy, Applied Thermal Engineering, Energy.