Application of Cryogenic Heat Pump in Reservoir Water Source Heat Pump System

The success of the development of the deep blue ultra-low temperature unit type hot and cold wind type ground source heat pump has greatly expanded the application field of the ground source heat pump. Conventional groundwater-based ground source heat pump uses 15 ℃ groundwater as heat source of air-conditioning system in winter, with stable performance, high energy efficiency and low system operation cost. However, exploitation of groundwater is highly specialized and risky. The prohibition of exploitation of groundwater in many areas has greatly restricted the application and promotion of ground-source heat pumps. The surface water due to low winter temperatures, it is difficult to apply in unit ground source heat pump system, deep blue ultra-low temperature unit type ground source heat pump to fill this gap.

Zhejiang Linhai City, Niutoushan recommended central air-conditioning company projects require the use of reservoir water as a cold source of air-conditioning, dark blue air conditioning in the fierce market competition, with its strong product technology and business advantages, won the bid in one fell swoop, dark blue Ultra-low temperature unit type ground source heat pump to get another typical user.

The construction project of Niutoushan Water Conservancy Construction Company in Linhai City, Zhejiang Province is close to Niutoushan Reservoir in Linhai City and the reservoir water level is higher than that of buildings. The project consists of 3 single buildings with the functions of respectively: hotels, office buildings and conference centers. The total construction area of ​​7000m2, building height of 5 layers. Reservoir water surface above the building ground 33m, you can use the natural elevation of water supply, reservoir water clear winter, winter can be used directly open. The actual measured value of the water temperature of the reservoir: At the ambient air temperature of 5.7 ℃, the water temperature is 13.8 ℃, the water temperature of the reservoir is higher than the ambient air temperature of 8.1 ℃, and the dry-bulb temperature of the winter air-conditioning outdoor calculation of the Linhai City is -1 ℃. According to a simple calculation, if the water temperature and air temperature remain the same temperature difference, then the winter Niutoushan reservoir minimum water temperature is 7 ℃. Relative to the ultra-low temperature ground source heat pump is still a high grade of heat source body.

The project design air conditioning cooling load 670kW, air conditioning heat load 450kW, part of the hotel hot water load 160kW. According to the characteristics of this project, the use of ground source heat pump to provide domestic hot water can greatly save hotel energy costs. The project uses 156 units of unit ground source heat pump hot and cold air units, including 10 ground source heat pump fresh air units and 2 ground source heat pump hot water units. System flow as shown below:

In order to prevent the summer reservoir water turbidity due to rainfall, the summer air-conditioning closed loop system, heat exchanger plate heat exchanger, the second closed water cycle to prevent scaling, as the domestic hot water unit in summer to heat the water body, A portion of the air conditioning system can be recycled to condense heat. In the primary water intake system of the reservoir, the water intake pump is provided with a bypass pipe. When the natural pressure head of the reservoir can satisfy the loss of water resistance of the system and the system circulation can be maintained, a water intake pump can stop the pump and directly utilize the natural water level pressure head of the reservoir. Only when the water level of the reservoir drops seriously, the water pump is used only once to save the energy consumption of the water pump.

In winter, due to the actual investigation in the field, the reservoir water body is very clear and can be directly used and opened. At this moment, if the natural water head of the reservoir meets the system circulation requirements, the reservoir diversion pipe is directly supplied to the secondary water supply main pipe of the air- When the water level in the reservoir is too low, it can be circulated through the secondary circulation pump of the original closed system. Domestic hot water unit winter also maintained open cycle.

The project makes full use of natural resources, compared with conventional central air-conditioning system to save the cooling tower and boiler investment, a substantial savings in the operating costs of air conditioning systems and domestic hot water operating costs, ground source heat pump system is worth promoting a typical application Case.