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

Abstract

Nowadays, a high amount of industrial thermal energy is still lost due to the lack of competitive solutions for energy revalorization. Facing this challenge, this paper presents a novel technology, based on a reversible High-Temperature Heat Pump (HTHP) and Organic Rankine Cycle (ORC). The proposed system recovers low-grade waste heat to generate electricity or useful heat in accordance with consumer demand. Compressor and expander semi-empirical models have been considered for the reversible system computational simulation, being HFC-245fa the working fluid selected. The built-in volume ratio and Internal Heat Exchanger (IHX) effectiveness have been optimized to reach the maximum energy efficiency in each operating condition. Although HFC-245fa exhibits energy performance attributes, its high Global Warming Potential (GWP) is an issue for climate change mitigation. Hence, multi-objective optimisation of the environmentally friendly working fluids Butane, Pentane, HFO-1336mzz(Z), R-514A, HCFO-1233zd(E) and HCFO-1224yd(Z) has been carried out. The results show that the system proposed, working with HFC-245fa, achieves a Coefficient of Performance (COP) of 2.44 for condensing temperature of 140 °C, operating in HTHP mode, whereas the ORC mode provides a net electrical efficiency of 8.7% at condensing temperature of 40 °C. Besides, HCFO-1233zd(E) and HCFO-1224yd(Z) are both appropriate alternatives for the HFC-245fa replacement. These working fluids provide a COP improvement of 9.7% and 5.8% and electrical net efficiency improvement of 2.1% and 0.8%, respectively, compared to HFC-245fa. This paper provides a reference study for further designs and developments of reversible HTHP-ORC systems used for industrial low-grade waste heat recovery.

Rankine Carnot Batteries with the Integration of Thermal Energy Sources: A Review

“…Such a configuration has been proposed and investigated by several authors in the literature, e.g., [47,60,61]. However, a detailed analysis of the technology for non-storage applications can also be found in [62][63][64][65]. The fully reversible TI-PTES layout can be found in Figure 8b.…”

“…In fully reversible TI-PTES, the most sensitive component is the reversible compressor/expander. The technology was verified experimentally in [63], where a reversible scroll machine was tested. For pressure ratios higher than 2.5-3, in both the operating modes, the machines achieved isentropic efficiencies around 0.6 or slightly higher and a filling factor near to one.…”

Exergy, Economic, and Life-Cycle Assessment of ORC System for Waste Heat Recovery in a Natural Gas Internal Combustion Engine

“…Several relevant works have been oriented for the development of theoretical models of waste heat recovery systems with organic Rankine cycles [24][25][26]. In this order of ideas, research into new configurations of the organic Rankine cycle to recover residual heat in the exhaust gases in an internal combustion engine, is benefited by these.…”

“…where Y w f i is the environmental impact of the amount of working fluid used in each component, which is the function of the exergy destruction of each component and is calculated using Equation (25).…”

Dynamic Modelling and Techno-Economic Assessment of a Compressed Heat Energy Storage System: Application in a 26-MW Wind Farm in Spain

“…In this work, a value of 4.2 kJ/kgK was employed for the specific heat of water, Cp w . The discharging process is relatively similar, as indicated by Equation (11). The volume of water available in the HTWT (V_w_HTWT) is compared against its maximum capacity (V_w_max_SHS) to assess if the value of P_q_sen_ORC is equal to P_q_sen_est_ORC or zero.…”