Underground Dagangshan Hydropower Plant Thermal Calculation And Its Energy-saving Research

Utilizing rock mass to cool or heat air can significantly save energy of air-conditioning system of underground hydropower station. It's important to calculate heat exchange inside underground spaces for determining air-conditioning system of hydropower station. At present, the country make demands on energy saving, thus, the research on the thermal calculation of underground spaces is realistic significance.In this thesis, the cavern group inside Dagangshan hydropower station is classified. After appropriately simplified, two physical models, equivalent cylinder model and plate model, are built. Using the concept of the heat resistance and heat capacity, and applying the energy conservation law to each control-volume, the numerical model is built. The dynamic thermal simulation program is written independently. Based on this program, two different schemes, ventilation system and air-conditioning system, are analyzed.The simulation of ventilation scheme of ten years period indicates that the indoor thermal environment does not change obviously after the long period running. The maximum air temperature of the powerhouse is 31.1℃. If the design temperature of the powerhouse is 26℃, the rate of the mean hours that are not guaranteed in ten years is 16%. the rate of the mean hours of temperature above 30℃, design temperature, in hydro turbine room is 9%, furthermore, the hours of produce-dew are rather more, the rate is 42%. The rate alike in snail shell room is 28%. Thus, the air-conditioning system is needed.The simulation of air-conditioning scheme indicates the air temperature of every cavern meet the requirement while the air-conditioning is set up in the powerhouse. In the condition of the satisfied annual energy consumption, the minimum air volume is found. It is 480,000m~3/h, less than 560,000m~3/h obtained from the traditional design method. Apparently, the energy consumption is less relatively. Accordingly, the operate mode of the air-conditioners and the whole satisfactory energy consumptions are also found.The model put forward in this thesis applied to deep-buried cavern's thermal calculation is acceptable and practical. It reflects the basic law of heat exchange. The outcome of the dynamic simulation program is quite abundant and also helpful to the design of energy conservation. Because it's the dynamic simulation, the result is precise and distinct.