Numerical Simulation And Experiment Analysis Of Indoor Thermal Environment With Radiant Floor Heating System

With the continuous improvement of people's living standards,the comfort of current building heating ways has gradually aroused people's attention. Low- temperature radiant floor heating system is being widely used in the northern region of China because of its comfort, energy saving, health and other advantages. In recent years, it also has the trend of development in hot summer and cold winter areas. At present, air-conditioning is being widely used for heating in hot summer and cold winter areas. This heating method'heat transfer form is mainly convection, which is high energy consumption, and is being widely criticized by the users because of its bad comfort. Radiant floor heating method is different from the traditional convection heating method, because the entire floor surface releases heat in the form of radiation and convection as the heating surface. Thus researching on the human thermal comfort in radiant floor heating environment can help us have a better understanding of the system; and it can provide guidance for the project design. In order to understand indoor thermal environment in the radiant floor heating way more fully, this paper adopts PMV-PPD evaluation index to evaluate human heat comfort in the floor heating environment, on the basis of analyzing the floor heat transfer mechanism and the basic knowledge of thermal comfort. At the same time, air conditioning heating method is compared.This paper makes use of Airpark software, takes one suit of office in Changsha with the air-source heat pump radiant floor heating system as study object, takes measured values as boundary conditions, establishs two kinds of mathematical models of floor heating and air conditioning heating. It uses numerical simulation method, analyses and compares indoor thermal environment (temperature, velocity, PMV(Predicted Mean Vote)-PPD(Predicted Percent Dissatisfied )) of the radiant floor heating mode and air conditioning heating mode. And it compares measured values with simulation results, educes the indoor thermal environment characteristic of the floor heating mode and air conditioning heating mode. The results show that the distribution of indoor temperature field and speed field is uniform in floor heating room, of which thermal comfort is good, and it can meet international standards of ISO7730 recommend PMV-PPD value. Comparing with air-conditioning heating mode, indoor thermal comfort of the floor heating mode has obvious advantage. Comparing with Measured value and simulation results show that the simulation values are in good agreement with the measured values,and simulating indoor thermal environment by the CFD simulation is feasible.Finally some factors of thermal enviroment are measured in the heating Office. The temperature of indoor, envelope surface and water-supply and backwater of the heat pump under initial operation, continuous operation and intermittent operation condition are measured, and the operation characteristic and actual heating effects of air-source heat pump radiant floor heating system in hot summer and cold winter area are learned. Measured results indicate: The heat pump unit preheat time is long, needs approximately six hours for the temperature of water-supply and backwater of the heat pump to come to a steady state. During continuous operation, the indoor temperature is more stable with smaller fluctuation, indoor warm feeling is better compared with intermittent operation .Under the same thermal comfort conditions, intermittent operation mode is beneficial to energy conservation.