Heat dissipation models by convection and radiation during the real-time operation of office equipment: A case study of computers

Abstract

For the reduction of building energy consumption and the higher operation efficiency of air-conditioning systems, dynamic heat dissipation of equipment by convection and radiation need to be precisely quantified, and the reasons are twofold: On the one hand, they accounted for approximately 20% of the cooling demand of office buildings; On the other hand, they are necessary for depicting the heat storage-release process of thermal masses, which is crucial to the description of instantaneous cooling demand. However, existing methods are hard to accurately describe the variation characteristics or time-delay effect of convective/radiative heat dissipation of equipment, resulting in limited applicability. To address this problem, in this study, models of equipment heat dissipation by convection and radiation during the real-time operation were first established as seventh-order transfer functions. Secondly, an experiment was conducted, and computers were selected as samples. Thirdly, experimental results were adopted in parameter identification and order analyses of proposed models. After that, the proposed models were validated under experimental and actual working conditions, with the MAPE (Mean Absolute Percentage Error) values being ≤ 8.51%. Finally, a performance comparison between the proposed and existing models was carried out. The proposed models achieved a time delay of about 1 h and a maximum heat dissipation reduction of 33.89%. With only one easily accessible and nearly free input, the proposed models demonstrated promising applicability and feasibility during the real-time operation. This study facilitates the calculation of dynamic cooling demand and contributes to the energy conservation of office buildings.