Applicability Study On Low Temperature Radiant Floor Heating Of Large Space Building In High Altitude Cold Regions

Due to its unique geographical conditions, high altitude cold regions has the characteristics of high altitude, low air pressure, low temperature, long winter, long heating period and high proportion of building energy consumption. In the high altitude regions, the heating energy consumption of the common heating end equipment in the large space building whether be affected by the climate conditions, there has few former research. Based on a low-temperature radiant floor heating system of the large space building which located in Shigatse, we have studied this question. This study will provide a reference for the application of low-temperature radiant floor heating system of large space buildings in high altitude and cold regions, and has guiding significance of selection and control of heating end equipment in high altitude and cold regions.In this paper, the author firstly summarizes the law of the variation of air performance with the change of altitude. Only the air density, atmospheric pressure, the temperature coefficient and the kinematic viscosity change with the altitude. The other thermal parameters are independent of the altitude.Secondly, this paper analysis the theoretical of the heat transfer process of the common heating ends of the large space buildings(fan coil and low temperature floor radiation), and then conclude a rule of the heat transfer coefficient varies with the altitude. Compared with the heat transfer coefficient of low temperature floor radiant heating system, the heat transfer coefficient of the fan coil unit decreases more quickly with the altitude, and the heat of the low temperature floor radiation heating system is less affected by altitude.Thirdly, using the energy simulation software—eQUEST, this paper establishes the model of water source heat pump with low-temperature hot water floor radiant heating system and water source heat pump with fan coil heating system in the Shigatse airport. And based on this model, this paper analyzes the energy consumption, changes the location of the building to Beijing area which winter outdoor air temperature similar to Shigatse area and then analysis the two heating systems energy consumption. Through analysis and comparison, we draw a conclusion that, compared to the plain area, the energy consumption of the fan coil unit is increased more than the low temperature floor radiation heating system in the high altitude area. In contrast, the low temperature floor radiation heating system whose heat transfer is less affected by altitude is more suitable for use in high altitude area.Then, this paper has experimented and tested the Lhasa airport fan coil heating system and Shigatse airport low temperature radiant floor heating system, analyzed the system energy consumption and indoor temperature distribution. In the course of the experiment, it is found that the design of the heating system without the influence of the high altitude on the coil heat exchanger can't meet the requirement of the interior design, and the low temperature floor radiation heating system which is not considered the altitude influences to the heating effect can reach the design requirements. This find verifies the results of theoretical analysis.Finally, this paper analyzes the optimization of the temperature of supply and return water temperature of low temperature floor radiant heating system. Using Fluent Airpak to establish the model, analyzing and comparing the temperature distribution of different supply and return water temperature conditions, and analyzing the energy consumption of the system under different supply and return water temperature conditions. Though comparing the thermal comfort and energy saving of different supply and return water temperature, the optimal temperature of water supply and return is 42?/37?.