Methodology research on solving non-steady state radiation heat transfer in the room with Ceiling Radiant Cooling Panels

• A method was provided to solve non-steady state indoor radiation heat transfer of CRCP.
• Further improvement of Gebhart method was made for solving the problem.
• Matrix equations of discrete-time were established to solve non-steady state.
• The limits that temperatures of all the surfaces must be given were broken.

Long wave radiation heat transfer is the dominant cooling mode of the Ceiling Radiant Cooling Panels (CRCP). This unique cooling mode makes the calculation of indoor long wave radiation heat transfer extremely important. Actually, indoor radiation heat transfer is usually under non-steady state conditions. General calculation methodology (simplifying radiation heat transfer or using the equivalent network method of steady state) is complex and less accurate when solving this kind of problem. In addition, general methodology fails to solve the situation that the temperatures of some interior surfaces are lacking but the heat flows are known. This paper provides a calculation methodology improving the Gebhart method for modeling the non-steady state radiation heat transfer between indoor surfaces. Given parameter variations (temperature and net radiant heat flow) of the surfaces are transformed into discrete column vectors of unit time, and then matrix equations are established, which can greatly reduce the work. This methodology has been verified experimentally, which can be regarded as a theoretical basis for solving indoor non-steady state radiation heat transfer of CRCP systems.