Meramveliotakis George, Kosmadakis George, Karellas Sotirios
Thermal Hydraulics and Multiphase Flow Laboratory, National Center for Scientific Research Demokritos, Agia Paraskevi, 15341, Greece.
Laboratory of Steam Boilers and Thermal Plants, National Technical University of Athens, Athens, 15780, Greece.
Open Res Eur. 2022 Nov 28;2:49. doi: 10.12688/openreseurope.14658.2. eCollection 2022.
This work investigates a vapour injection scroll compressor integrated in a heat pump using the refrigerant R1234ze(E). The water-to-water heat pump was tested under a wide temperature range at the evaporator and condenser sides. The test results revealed that the performance is significantly reduced for lifts of over 30 K with the coefficient of performance being even below 2 and the maximum 2 law efficiency was just 28%. In order to enlighten the reasons behind such significant compressor underperformance, a semi-empirical model has been extended to include vapour injection, and a new improved modelling approach for the suction pressure drop was developed and implemented considering both the turbulent and laminar inlet flow regimes. Once the accuracy of the developed semi-empirical model was verified, the model was then adjusted to account for the R1234ze(E) operation, by fine-tuning its parameters based on the test data. The main loss mechanism identified is the high suction pressure drop, due to the high friction factor, with the inlet refrigerant flow possibly being laminar instead of turbulent. This resulted in a significant reduction of the mass flow rate and volumetric efficiency, while the standard model for suction pressure drop was not able to capture this effect.
本研究对一台集成于使用制冷剂R1234ze(E)的热泵中的蒸汽喷射涡旋压缩机进行了研究。该水-水热泵在蒸发器和冷凝器侧的宽温度范围内进行了测试。测试结果表明，当压缩比超过30K时，性能显著降低，性能系数甚至低于2，最大卡诺效率仅为28%。为了弄清楚压缩机性能如此显著下降背后的原因，一个半经验模型被扩展以包含蒸汽喷射，并开发并实施了一种新的改进的吸入压降建模方法，该方法同时考虑了湍流和层流入口流动状态。一旦所开发的半经验模型的准确性得到验证，便根据测试数据对模型进行微调，以使其适用于R1234ze(E)的运行。所确定的主要损失机制是由于摩擦系数高导致的高吸入压降，入口制冷剂流可能为层流而非湍流。这导致质量流量和容积效率显著降低，而吸入压降的标准模型无法捕捉到这种影响。
