Heat pumps for combined heating and cooling in industrial applications: A generalised approach
Martin Pihl Andersen, Benjamin Zühlsdorf, Wiebke Brix Markussen, Jonas Kjær Jensen, Brian Elmegaard
Abstract
• A method is proposed to evaluate simultaneous heating and cooling systems. • Lower and upper break-even points are defined where HPSs are promising. • Heating demand needs to be between one and ten times the cooling demand. • CCHSs electricity savings heavily depend on COPs and fan power. • Flexible systems are essential to ensure the greatest performance. Climate change necessitates the urgent adoption of cleaner, sustainable energy solutions in industrial settings. This study evaluates Combined Cooling and Heating Systems (CCHSs) to simultaneously provide heating and cooling, aiming to improve energy efficiency and reduce overall electricity consumption. By utilising a simplified thermodynamic model, the work assesses the general potential of CCHSs compared to alternative solutions for fully electrifying industrial applications. The analysis demonstrates significant energy savings achievable through implementing a CCHS, ranging from 12 % to 34 %. However, optimal performance is contingent upon specific operating conditions. The upper and lower break-even points that define the optimal heating-to-cooling demand ratio for maximising CCHS benefits were found. Notably, maintaining a heating demand exceeding the cooling demand, within certain thresholds, was crucial for superior overall efficiency. Additional heat pump units or refrigeration cycles may be required to enhance CCHS performance in circumstances where the ratio between the heating and cooling demand does not fit the optimal point for the CCHS. Furthermore, the study highlights the importance of storage capacity for stabilising system operation. In conclusion, the findings underscore the potential of CCHSs to enhance industrial energy efficiency, outperforming separate heat pump and refrigeration cycles. However, realising their full potential requires a comprehensive understanding, meticulous design, and further research. While CCHSs offer a compelling pathway to a more sustainable industrial future, careful design considerations are essential to ensure superior performance compared to simpler solutions.