Injector

Waste heat recovery unit

Coefficient of performance

Vapor-compression refrigeration

Gas compressor

Engineering

Ecology

Biology

Global-warming potential

Waste heat

Evaporator

Economizer

Heat exchanger

Waste management

Mechanical engineering

Thermodynamics

Physics

Greenhouse gas

Nuclear engineering

Process engineering

Environmental science

Heat pump

Refrigerant

Energy Conversion and Management

High temperature heat pumps (HTHPs) have a great potential to improve industrial processes with thermal demand through industrial waste heat recovery and revalorization. Vapor compression HTHPs are very sensitive to the cycle configuration, refrigerant, components, and operating temperatures. This study compares eight advanced cycle configurations and nine low global warming potential (GWP) refrigerants from an energetic, economic, and environmental comprehensive perspective to illustrate an optimum selection for different HTHP applications. Firstly, several single-stage and two-stage compression cycles are proposed adding different components, such as the ejector, economizer, parallel compressor, flash tank, or additional evaporators and condensers. Moreover, an internal heat exchanger (IHX) has been included in all configurations to maximize the energy performance and ensure dry compression. Secondly, HC-601, HC-600, HC-600a, HFO-1336mzz(Z), HFO-1336mzz(E), R-514A, HCFO-1233zd(E), HCFO-1224yd(Z), and HFO-1234ze(Z) are considered as alternative low GWP refrigerants to replace the hydrofluorocarbon HFC-245fa. The results indicate that a two-stage cascade becomes the most appropriate configuration for high temperature lifts (60 K and above). In contrast, single-stage cycles with economizer and parallel compression are suitable for low temperature lifts (50 K and below). HCFO-1233zd(E) and HCFO-1224yd(Z) show a trade-off between coefficient of performance (COP) and volumetric heating capacity (VHC). Advanced HTHPs configurations can save up to 68% of the equivalent CO2 emissions compared to a natural gas boiler.

Advanced high temperature heat pump configurations using low GWP refrigerants for industrial waste heat recovery: A comprehensive study