کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6481133 | 1428939 | 2017 | 14 صفحه PDF | دانلود رایگان |
- Air- multiple phase change materials (PCMs) unit is investigated for the free cooling and ventilation of buildings.
- cp-T relationship of selected PCMs are determined from the Differential Scanning Calorimetry (DSC).
- CFD model applying the effective heat capacity method for the air-PCM unit optimization.
For the present paper the potential of an air- multiple phase change materials (PCMs) unit is investigated for the free cooling and ventilation of buildings. Firstly, a CFD model has been developed to determine the charging and discharging temperatures of the PCM as well as the air outlet temperature of an air-PCM unit. The effective heat capacity method is applied introducing the Cp-T relationship obtained from the Differential Scanning Calorimetry (DSC) and has been validated by experimental results. Secondly, the validated model has been further extended for multiple PCMs to investigate the thermal performance enhancement incurred by using multiple PCMs for free cooling application. The model takes into account the daily temperature profile and therefore a variable temperature is coupled to the air inlet boundary condition. Thirdly, a parametric study has been conducted to investigate the effect of multiple PCMs within the panels, followed by the effect of geometry e.g. height, length and the charging and discharging air mass flow rates.The proposed best case design is a combination of RT20 and RT25 with geometric dimensions of HÂ =Â 0.03Â m and LÂ =Â 1.5Â m and an air mass flow rate of 0.25Â kg/s. The unit presented a thermal energy varying from 0.4 to 1.46Â kJ over 8Â h, with an average thermal energy of 1.02Â kJ. The average effectiveness of the unit is 0.5, remaining similar to this value for over 6Â h. In order to make the proposed unit competitive in terms of energy consumption and running cost, the charging process of the PCM has to be improved during night time leading to high air mass flow rate requirement.
Journal: Energy and Buildings - Volume 151, 15 September 2017, Pages 520-533