Establishment and Study on the Simplified Model of Unsteady Heat Transfer of Concrete Radiant Cooling Systems
|Course||Heating , Gas Supply, Ventilation and Air Conditioning Engineering|
|Keywords||Concrete radiant cooling Unsteady heat transfer Geometry and thermal parameters RC simplified model FEM|
One important difference between concrete radiant cooling system and other types of radiant cooling system is that, for concrete system, the pipes are direct contact with the concrete slab. As part of the air conditioning system, concrete slab directly involved in the heat transfer process between the air conditioning system and the rooms. The heat storage of the concrete slab will complicates the heat transfer process and directly affects the system’s cooling performance and operation strategy.The research methods of unsteady heat transfer in concrete radiant cooling system include numerical methods and simplified model methods. While numerical methods provide quite accurate solutions but they are very time-consuming. Some of the existing simplified models need use the results of numerical methods as their known conditions. The main objective of this dissertation is to create a method which establishes the simplified models according to the geometry and thermal parameters rather than the result of numerical methods. Using the relevant research results, the author establishes one RC simplified model and writes the computer program with the help of MATLAB. And then, in order to test the accuracy and find the applicable scope of the RC simplified model, a FEM numerical model is established. In the last part, the author also discusses some common issues of the system design and operation by using the RC simplified model.Four conclusions and results are concluded. Firstly, RC simplified model and MATLAB computer program are established and written. Secondly, with the help of a FEM numerical model, the author come to the conclusion that RC simplified model has good accuracy and the applicable scope can cover the common types of the concrete radiant cooling systems. Thirdly, the author discusses the relation between the geometric parameters and the cooling performance of the system. In the end, the author also calculates the thermal retardation time of the concrete slab cooling system and capillary cooling system when the supply water temperature in the step change condition.