Decarbonization of industries using reverse brayton high temperature heat pumps: A case study in the ceramic industry

A closed-loop Reverse-Brayton High Temperature Heat Pump with air working medium is studied and optimized considering real operating conditions for a ceramic industry. The heat pump was considered to upgrade the waste heat of the kiln’s exhaust gases into useful heat for further heating up the combustion air. All the necessary thermodynamic variables are determined by calculating the compressor and turbine work, the input power, the coefficient of performance, and the exergy efficiency. First, a detailed optimization procedure is carried out for various inlet preheated air temperatures in the range of 100–200 °C, with the primary aim being the maximization of the heat pump performance (COP maximization) by identifying the optimal working-medium mass flow rate for each preheated air temperature level. Secondly, for the defined optimized operating conditions, a dynamic analysis was performed for a typical week of operation, considering real data with inlet preheated air temperatures within the range of 106.8–179 °C (typical week fluctuation) and considering operation under optimized mass flow rate values. It was found that the integration of HTHP leads to 1.36% primary energy savings and 5.44% CO 2 emissions reduction on a yearly basis, ensuring a slightly lower annual operating cost than the respective of natural gas combustion.