| With the improvement of people’s living standard,building energy consumption is increasing and conventional energy resources grow scarcity,floor radiant heating equipments which have energy saving property and comfortableness as well as other advantages have been applied more widely in heating buildings.China released the first test standard for thermal performance of radiant heating unit JG/T 403-2013 《Test methods for thermal performance of radiant cooling and heating unit》 in 2013,the test methods are still developing.Because of the variety of actual heating environment,in the promotion process related technology may not offer exact design parameters to designer according to current standards,which affects the system’s final use effect.In this paper,based on the research status of test technology for thermal performance of radiant heating unit at home and abroad,the heating load of floor radiant heating unit test sample under the Chinese test standard is revised by numerical simulation and experiment.First,this paper interprets the structure and heat transfer principles of floor radiant heating equipments.On the basis of reasonable simplification,a heat transfer mathematical model of floor radiant heating system is carried out.Simultaneously,the basic governing equations,turbulent transport equation,radiant heat transfer equation and single valued conditions are also presented,solved by ANSYS software.By experiment for thermal performance of floor radiant heating unit test sample at the standard laboratory in National Air Conditioning Equipment Testing Center,the reliability of the mathematical model is verified.Second,this paper makes a detailed comparison of current test standards for thermal performance of radiant heating unit at home and abroad,JG/T 403-2013,EN 14037,ANSI/ASHRAE 138 and BLT HS/B-b-8.Using the proven mathematical model,the same floor radiant heating unit test sample is calculated of numerical simulation under the above different test standards respectively.Comparing the simulation results,there is 5%~11% difference between them.Non-heating wall temperature is presented,which is the mainly environment parameter affects the measured heating load under different test standards.Finally,using the above mathematical model,the floor radiant heating unit test sample is calculated of numerical simulation under different non-heating wall temperature conditions.A new variable,the temperature difference between average water of test sample and area weighted mean of non-heating wall,is introduced to revise the heating load characteristic formula fitted under the Chinese test standard JG/T 403-2013.The revised formula can offers exact design parameters under different nonheating wall temperature conditions,providing suggestion and a reference for developing of Chinese test standard for thermal performance of floor radiant heating unit. |
