研究目的
To reduce energy consumption in DHW applications by using supercooled PCMs and a novel operation controlling methodology, and to operate the systems in a more sustainable way by implementing solar assisted heat pump units.
研究成果
The results show that the PCM tubes effectively compensate the morning peak hot water demand and reduce daily energy consumption around 12.1% and 13.5% by shifting heating provision from immersion heater to solar heat pump. The proposed novel control method of the supercooled PCMs can provide required heat for the morning hot water demand and it can reduce daily DHW energy consumption by about 12.1-13.4% according to weather conditions.
研究不足
The study focuses on the performance improvement of solar assisted heat pump hot water system by novel controllable crystallisation of supercooled PCMs. The limitations include the specific weather conditions (summer and spring in the UK) and the specific type of PCM (sodium acetate trihydrate) used in the study.
1：Experimental Design and Method Selection:
A transient thermodynamic model is built for the whole system including solar collector, heat pump, water tank with PCM and DHW demand profile. System components are modelled and a 24 hours of demand profile is used in simulation for a UK home for summer and spring weather conditions.
2：Sample Selection and Data Sources:
The UK DHW consumption pattern was measured and identified in a report by Energy Saving Trust. The reference reported that the mean household consumption was 122 litre hot water per day and the average hot water delivery temperature was 51.9℃.
3：9℃.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Solar collector (Thermomax HP-200 evacuated-tube heat pipe collector), heat pump (water source heat pump unit), water tank with PCM (cylindrical PCM modules), and DHW demand profile.
4：Experimental Procedures and Operational Workflow:
The system operates in two modes. Heat pump is active in the first mode and direct solar heating happened in the second mode. To determine these operation modes, temperature of the top node in the water tank has been considered.
5：Data Analysis Methods:
Energy balance equations for all components and heat transfer equations are written in Matlab environment, for refrigerant thermophysical properties, Refprop software is used.
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