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Refrigerant Circuitry Optimization of Heat Exchangers for Charge Reduction and Robust Performance in Reversible Heat Pump Application.

Number: No 109

Author(s) : LI Z., AUTE V., LING J.

Summary

Heat pumps are becoming more and more desirable around the world as an efficient mean of space conditioning for both cooling and heating requirements. Heat exchangers (HXs) are the key components in these devices and pose some unique design challenges because the same HX has to operate as an evaporator in one mode and as a condenser in the other. Studies have proved that by optimizing the refrigerant circuitry, the performance of HXs can be significantly improved. In a reversible heat pump application, the optimal circuitry obtained under the air conditioning (AC) mode cannot guarantee optimal performance if it is used in the heat pump (HP) mode. Our study shows that the single objective optimal design obtained under AC mode yields 11.4% capacity degradation when it is used in HP mode. This paper presents a multi-objective refrigerant circuitry optimization approach to achieve robust heat exchanger performance in both cooling and heating modes. This work builds on a newly developed Integer Permutation based Genetic Algorithm (IPGA), which can guarantee good manufacturability of optimal circuitry designs. The enhanced IPGA extends the capabilities to generate designs with splitting and merging circuits, thus exploring the design space thoroughly. Two multi-objective problem formulation is proposed. One formulation aims at minimizing refrigerant charge, and the other formulation aims at maximizing HX capacity. The optimal HX designs are analyzed at the system level as a part of a reversible heat pump simulation. A case study using an A-type indoor unit shows that the optimal design obtained using the formulation to minimize charge can yield charge reduction by 19.2% under AC mode and 21.6% under HP mode. The optimal design using the formulation to maximize capacity improves the cooling capacity by 2.3% and system COP by 2.5% under AC mode and meanwhile, improves the heating
capacity by 3.0% and system COP by 2.8% under HP mode. Considering the performance degradation of the single objective optimal, the effective capacity improvement of the bi-objective optimal is 14.4%. 

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  • Original title: Refrigerant Circuitry Optimization of Heat Exchangers for Charge Reduction and Robust Performance in Reversible Heat Pump Application.
  • Record ID : 30029987
  • Languages: English
  • Subject: Technology
  • Source: 13th IEA Heat Pump Conference 2021: Heat Pumps – Mission for the Green World. Conference proceedings [full papers]
  • Publication date: 2021/08/31

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