Real-Time Optimization of Integrated Subcooling Transcritical Co2 Heat Pump Water Heater Via Phasor Esc

Abstract

In this article, for the first time we introduced the phasor ESC to real-time optimization of integrated subcooling transcritical heat pump water heater as improvement of dither-demodulation ESC. We established a dynamic model with high-fidelity of the heat pump system in Dymola. Starting from the single phasor ESC for discharge pressure, we proposed the practical guideline of parameter tuning and the most important is that an optimal dither frequency exists in terms of the final stable performance. Due to capability of faster dither, the searching process was mostly shortened by 92.32%. The effectiveness and repeatability of multi-variable phasor ESC was demonstrated under both the static and the stair-change ambient temperature. In the final case of varying ambient temperature, the multi-phasor ESC always performs better than the constant-strategy and shows the superior following characteristics compared to the classic ESC. Under ambient temperature of three-times varying speed, the averaging COP of phasor ESC is 0.19% higher than that of the classic ESC.

Keywords: CO2 heat pump, Subcooling, Phasor estimator, ESC, Multi-variable