Combining measurements and simulation for condition monitoring and performance optimization of an alpha-configuration double-acting high-temperature Stirling cycle-based heat pump

For industrial applications, it is important to reliably monitor the condition of critical equipment and to run at optimal performance for varying operating conditions. Often important parameters for monitoring and optimization cannot be reliably measured and must be estimated. For example, there are great difficulties in measuring temperatures inside a Stirling cycle-based heat pump as these fluctuate between heating and cooling cycles at speeds of 10-12.5 Hz. Validation of models using full-scale industrial applications are very rare. We here present and validate a model for simulating cyclic temperature variations inside an industrial alpha-configuration double-acting Stirling cycle-based high temperature heat pump based on measured cylinder pressures and slow-changing temperature data. This will be used for online monitoring of the heat pump and as input to system performance optimization. The heat pump used as a reference is located in Gothenburg, Sweden with a design heat output of 500 kW and steam output at a temperature of 180 degrees C. The outputs of the model are temperature curves during a full cycle for both cold and hot side water and working fluid temperature variation in different parts of the machine. The model is validated against a different data set from the same system.