Evaluation of pentanes as refrigerants for heat pumps with sink temperatures above 130°C

This study examines the use of hydrocarbon refrigerants for high-temperature heat pumps (HTHP), aiming to decarbonize process heat. Synthetic refrigerants are being phased out due to their environmental impact, the need for natural refrigerants as alternatives is rising. Currently, n-butane can provide sink temperatures up to 130 °C, but in industrial processes higher temperatures are required and hydrocarbons are not yet evaluated in detail. In addition to n-pentane, there are its isomers: neo-, cyclo-, and iso-Pentane, showing significant differences in their thermodynamic characteristics. Even if they have been considered and used in both theoretical and practical research a concise comparison of these refrigerants is missing. This study will evaluate the group of Pentanes comparing their thermodynamic properties and application characteristics (e.g. explosion levels). The results will be discussed for typical process conditions (temperatures, temperature spreads) and specific requirements for the apparatus to be used in heat pumps with these refrigerants.