Analysis of the Application Example of Groundwater Source Heat Pump System
Groundwater source heat pump (GSHP) system is a kind of ground source heat pump technology, which uses groundwater or groundwater as the heat source of a ground source heat pump unit. The system uses the refrigerant in the unit as the medium, using the heat exchange principle of condensation and boiling in the cycle of the refrigerant, and uses the pressure difference between the high and low sides to achieve the conversion and utilization of thermal energy to realize the energy-saving and energy-saving effects of heating and cooling.
In this paper, the application examples of GSHP system are introduced from three aspects: basic components of GSHP system, common application systems and typical application cases.
1. Basic components of GSHP system
The basic components of GSHP system include GSHP exchange system, high and low temperature reservoir, delivery and return water pumps, temperature and humidity measurement system, central control system and other auxiliary control systems, etc. The system is set around the heat pump unit, so that the unit can operate safely and stably and take full advantage of the thermal energy of groundwater.
〖1〗GSHP Exchange System
GSHP exchange system is the basis of GSHP system. Its main components are heat pump unit, plate heat exchanger, and other auxiliary equipment such as electric meter, thermometer, and filter.
The heat pump unit captures the latent heat of groundwater or groundwater by using the working principles ofevaporation and condensation, and then converts it into heat or cold energy to satisfy the need of heating, cooling and sanitation. The operation of GSHP can be divided into two cycles: evaporator cycle and condenser cycle. In the evaporator cycle, the condensed liquid absorbs the heat in the ground and vaporizes, and then enters the compressor for compression refrigeration; in the condenser cycle, the high-temperature and high-pressure gas after compression enters the four-way reversing valve and transfers heat to the heat exchange system.
The plate heat exchanger is used to transfer heat to or from the GSHP system, or to supplement the cooling capacity of the system. With the increasing of installed capacity, the volumetric load on the heat pump unit decreases, and the coefficient of performance is improved.
〖2〗High-Low Temperature Storage System
The GSHP system with storage tank can achieve more efficient energy utilization by utilizing the thermal energy of the groundwater at low temperature in the night to preheat the refrigerant medium in the storage tank, so as to then achieve the purpose of maintaining the heating and cooling energy.
There are usually two storage tanks in the GSHP system, one is the high-temperature water tank, and the other is the low-temperature water tank. The high-temperature water tank is connected to the compressor outlet of the heat pump unit and the medium inlet of the middle connecting plate. The cold water tank is connected to the evaporator outlet of the heat pump unit and the medium outlet of the middle connecting plate.
〖3〗Delivery and Return Water Pumps
The circulation system of GSHP imports and exports water to the GSHP system. A water pump is required to ensure the circulation of water in the system.
The delivery and return pump can adjust the flow rate, in order to make the system maintain the safety and comfort of the user in different working states through its operation. The temperature of the water in the storage tank is automatically adjusted by the pump for heating or cooling.
〖4〗Temperature and Humidity Measurement System
The temperature and humidity monitoring system is used to determine the temperature of the medium in the GSHP system, the temperature of the water source, and the temperature of the well. According to the measured data, the system can control the operation mode of the heat pump unit and adjust its work parameters.
〖5〗Central Control System
The control system of GSHP can centrally control the temperature of the pipeline, the running state of the heat pump unit and its adjustment, the operation of the pump and the opening and closing of the four-way reversing valve. The central control system can also record the historical data of the system, so as to analyze and adjust it regularly for fault detection, energy optimization and other operations.
2. Common Application Scenarios
GSHP systems can be used for a wide range of applications, from individual high-end establishments and facilities to large commercial and industrial buildings. Common application scenarios are as follows:
〖1〗Supply air-conditioning equipment. GSHP system can be used as the main air-conditioning equipment in shopping malls, supermarkets, office buildings, hospitals, etc.
〖2〗Supply refrigeration equipment. GSHP system can be used to provide refrigeration equipment for cooling and preservation in hotels, hospitals, food processing, etc.
〖3〗Supply central heating equipment. GSHP system can be used as the main heating equipment in factories, schools, office buildings, hotels, etc.
3. Typical Application Case
GSHP system has been widely used in many projects. Here is a typical application case from a shopping mall in Xiamen:
The shopping mall is located in southern Xiamen. It is one of the largest commercial complexes in Xiamen. The GSHP system is used as the main air conditioning system of the shopping mall. The GSHP requires 4 sets of heat pump units, 4 sets of low-temperature water tanks, 4 sets of high-temperature water tanks, 8 sets of delivery and return water pumps, temperature and humidity measurement system, central control system and other auxiliary control systems.
The system utilizes the heat absorbed by the ground during the day and the higher temperature at night to preheat the refrigerant medium in the storage tank, so as to save the energy used by the air conditioning system of the shopping mall. The GSHP system has been energized since its completion and has brought a good energy-saving effect. In peak and air-conditioning seasons, electric energy saving rate can reach 20%.
Conclusion
Groundwater source heat pump system is a kind of ground source heat pump technology, which uses groundwater or groundwater as a heat source of a ground source heat pump unit. The system can heat and cool the indoor environment by using the thermal energy of groundwater according to the heat exchange principle of condensation and boiling, and it has the advantages of energy saving, safety, and pollution-free. In this paper, the application example of GSHP system is analyzed from the aspects of basic components, common application systems and typical application cases.
