Experimental exergy and energy analysis of a novel high-temperature heat pump with scroll compressor for waste heat recovery

Abstract

The industrial sector demands novel sustainable energy systems to advance in its decarbonisation and meet the targets of the Paris Agreement for the climate change mitigation. High-Temperature Heat Pumps (HTHPs) are being investigated as a feasible energy conversion technology alternative to traditional fossil fuel boilers. This paper presents the first experimental results of an HTHP prototype equipped with a modified scroll compressor and internal heat exchanger (IHX). The elements of the main and secondary circuits are presented, as well as the test methodology and heat balances are exposed. The tests have been performed using HFC-245fa at heat source temperatures between 60 and 80 °C, and heat sink temperatures between 90 and 140 °C. The heating capacity and coefficient of performance (COP) varied between 10.9 and 17.5 kW and between 2.23 and 3.41, respectively. An exergetic analysis indicated that the expansion valve was the component with the worst second law efficiency and the compressor presented the highest potential improvement over the other cycle components. A computational analysis of low global warming potential (GWP) refrigerant alternatives was carried out, which confirmed the benefits of using an internal heat exchanger (IHX) and the good performances of the low-GWP refrigerants: HCFO-1224yd(Z), HCFO-1233zd(E), and HFO-1336mzz(Z). Finally, we proved that the proposed system can save up to 57% of the equivalent CO2 emissions of a natural gas boiler. This paper provides a reference for the high-temperature heat pump recovery of the lowgrade waste heat from industrial energy processes.

Energy, Exergy, and Environmental (3E) Analysis of Hydrocarbons as Low GWP Alternatives to R134a in Vapor Compression Refrigeration Configurations

“…The total and specific exergy of a fluid were calculated using Equations ( 10) and ( 11), respectively [26]:…”

“…where Ex des, total is the total exergy destruction of the system. Another parameter that takes into account the contribution of each component of the system is relative irreversibility (RI) and can be defined for the component i using Equation ( 22) [26]:…”

Вибір Переохолоджувача Конденсату Парокомпресорної Холодильної Машини

“…Теоретично, при охолодженні конденсату до температури кипіння витрати на дроселювання будуть дорівнювати нулю і ефект від збільшення розмірів регенератора теж нульовий. Метод оцінки по ступеню термодинамічної досконалості, або ексергетичному коефіцієнту корисної дії найбільш поширений не тільки для регенератора, а і економайзера, зовнішнього переохолоджувача [4,5], в роботах поєднані натурні, числові та імітаційні методи моделювання.…”

Multi-objective optimization of a novel reversible High-Temperature Heat Pump-Organic Rankine Cycle (HTHP-ORC) for industrial low-grade waste heat recovery

“…Therefore, isentropic and volumetric efficiencies are adjusted using Eqs. ( 2) and ( 3), considering that the refrigerant inside the compressor or expander can be considered as an ideal gas [34].…”

“…HTHPs are still in an earlier stage of development, and the first results using different types of prototypes, compressor technologies, working fluids, and configurations are being published. Mateu-Royo et al [34] have developed an HTHP prototype with scroll compressor that provides a Coefficient of Performance (COP) of 2.23, working with a heat sink and source temperatures of 140 and 80 ºC, respectively. Moreover, Bamigbetan et al [35] present the development of hydrocarbon HTHP with internal heat exchanger and receiver to produce useful heat at 115 °C using HC-600 as working fluid.…”