About the principle of ground-source heat pumps! (Weekly Topic) Warm discussions are welcome

This post was last edited by sailan on 2011-5-16 10:51. A geothermal heat pump is a technology that uses the underground soil layer as a cold (hot) source to provide heating, hot water, and air conditioning for buildings. As is well known, the temperature beneath the strata remains relatively stable throughout the four seasons. In summer, the temperature underground is lower than that of the air at the surface, while in winter it is higher than the air temperature at the surface. A geothermal heat pump makes use of this property of the earth, exchanging heat with the soil or rock through heat exchangers buried underground. Geothermal heat pumps operate stably throughout the year; they can provide heating in winter and cooling in summer without the need for any additional heat sources or cooling equipment. Therefore, ground-source heat pumps are a new technology that is efficient, energy-saving, environmentally friendly, and conducive to sustainable development; they neither pollute groundwater nor cause land subsidence. In winter, the liquid inside the pipes draws heat from underground and transfers it into buildings through the system, while storing cold energy for use in summer ； In summer, heat is extracted from the building and discharged underground through the system, while heat is stored for use in winter. Geothermal heat pumps can reliably provide high-quality cooled and heated air throughout the year, creating a very comfortable indoor environment for us.

Geothermal heat pumps have been the subject of discussion for many years; it is known that they have significant advantages over electric heating and coal heating in terms of energy consumption. However, in terms of actual applications, no detailed cost analysis is available – there are no precise figures regarding capital investment costs or the expenses associated with system operation and maintenance. In my opinion, ground-source heat pumps still have their shortcomings; otherwise, with so many industrial and real estate projects around today, why is the use of ground-source heat pumps so limited?

A ground-source heat pump is an efficient and energy-saving air conditioning system that utilizes shallow geothermal resources (also known as geothermal energy, including groundwater, soil, or surface water) to provide both heating and cooling. A geothermal heat pump transfers heat from a lower temperature level to a higher temperature level by using a small amount of high-quality energy source, such as electricity. Geothermal energy can be used in winter as a heat source for heat pumps to provide heating, and in summer as a cold source for cooling. That is, in winter, the heat contained in geothermal energy is extracted, increased in temperature, and then supplied to the interior for heating purposes ； In summer, the heat inside the building is removed and released into the geothermal energy. Typically, a ground-source heat pump consumes 1 KW of energy, allowing the user to obtain more than 4 KW of heat or cooling. 　　 Geothermal heat pump: A geothermal heat pump transfers heat from a lower temperature level to a higher one by using a small amount of high-quality energy (such as electricity). Geothermal energy can be used in winter as a heat source for heat pump heating, and in summer as a cold source for air conditioning; that is, in winter, the heat contained in geothermal energy is extracted, elevated in temperature, and then supplied to the interior for heating ； In summer, the heat inside the building is removed and released underground. Typically, a ground-source heat pump consumes 1 kW of energy, allowing the user to obtain more than 4 kW of heat or cooling.

This post was last edited by sailan on 2011-5-16 10:53. A geothermal heat pump is a technology that uses the underground soil layer as a cold (hot) source to provide heating, hot water, and air conditioning for buildings. As is well known, the temperature beneath the strata remains relatively stable throughout the four seasons. In summer, the temperature underground is lower than that of the air at the surface, while in winter it is higher than the air temperature at the surface. A geothermal heat pump makes use of this property of the earth, exchanging heat with the soil or rock through heat exchangers buried underground. Geothermal heat pumps operate stably throughout the year; they can provide heating in winter and cooling in summer without the need for any additional heat sources or cooling equipment. Therefore, ground-source heat pumps are a new technology that is efficient, energy-saving, environmentally friendly, and conducive to sustainable development; they neither pollute groundwater nor cause land subsidence. In winter, the liquid inside the pipes draws heat from underground and transfers it into buildings through the system, while storing cold energy for use in summer ； In summer, heat is extracted from the building and discharged underground through the system, while heat is stored for use in winter. Geothermal heat pumps can reliably provide high-quality cooling and heating air throughout the year, creating a very comfortable indoor environment for us

The principle is similar to that of an air conditioner, except that the external unit of the air conditioner is replaced with groundwater. Since the temperature of groundwater remains relatively stable throughout the year (15–25°C), it provides heat to users in winter and cooling in summer. However, ground-source heat pumps have higher cooling and heating coefficients than conventional air conditioners; while ordinary air conditioners have coefficients of 2.5 to 3.5, ground-source heat pumps can reach around 5. As a result, they are more energy-efficient, though the initial investment is much higher. They are therefore a cost-effective option for large-scale users.

Working principle: Geothermal heat pump technology makes use of the low-grade thermal energy stored in the soil (rock) and water bodies (groundwater, oceans, rivers, lakes, etc.) at the Earth’s surface, which has been accumulated through the absorption of solar energy and geothermal energy. By applying the principles of heat pumps, this technology enables the transfer of low-grade thermal energy to higher-grade thermal energy with only a small amount of electrical energy input. In central air conditioning systems, heat pump units can serve three functions simultaneously: in winter, they release heat through the condenser to provide heating; in summer, they absorb heat via the evaporator to cool the space. Throughout the year, hot water for domestic use can be generated using the heat from the condenser, and when used for cooling in summer, the production of hot water can be considered cost-free. Geothermal heat pump central air conditioning units represent a new technology that is efficient, energy-saving, environmentally friendly, and conducive to sustainable development; they neither pollute groundwater nor cause ground subsidence. Every type of equipment has its operating temperature range, and the same is true for humans; if the environmental temperature exceeds the range within which humans can survive, they cannot live either. The same is true for air conditioning and refrigeration systems. The temperature operating range of the air conditioning system is such that, during cooling in summer, the condensation temperature of the condenser (the outdoor unit) is 42℃ ； During winter heating, the evaporation temperature of the evaporator (indoor unit) is -5°C. Beyond this temperature range, the cooling efficiency decreases in summer, while the heating efficiency decreases in winter. This is why air conditioners are not suitable for heating in the northern winters. It is well known that during summer, the temperature of the ambient air is higher than that of the local groundwater, surface water, and soil, while in winter, the ambient temperature is lower than that of these same water bodies and soil. Soil functions as a reservoir for heat and cold; the deeper it is underground, the better its temperature-stabilizing effect. Ten meters below the surface, the underground temperature remains around 13°C, regardless of whether it is winter or summer. Therefore, during summer, when the ground-source heat pump air conditioning system is in cooling mode, groundwater is used to cool the condenser ； In winter, ground-source heat pump air conditioning systems use groundwater to raise the temperature of the evaporator during heating. This not only improves the efficiency of the air conditioning system but also enhances its cooling/heating performance; more importantly, it also helps to save energy. Based on our experience, well-designed and installed ground-source heat pumps can help users save an average of 30% to 40% on their heating costs in winter or air conditioning costs in summer. Soil-source heat pump air conditioning, also known as geothermal heat pump air conditioning, involves installing pipes underground to serve as heat exchangers. These pipes are connected to the heat pump unit to form a closed loop; fluid flows within these pipes, and through circulation, the heat generated by the heat pump unit is dispersed into the ground during cooling mode, or heat is drawn from the ground to supply the heat pump unit for heating buildings in heating mode. There are various types of soil-source heat pump exchangers, such as horizontal buried pipes and vertical buried pipes. These two types of buried pipes each have their own characteristics and application scenarios. In China, the use of vertically buried pipes demonstrates even greater advantages: they save space, offer excellent heat exchange performance, and can be installed beneath building foundations, roads, green spaces, squares, playgrounds, etc., without affecting the functionality of the areas above. In fact, such pipes can even be placed within building piles, allowing for makeuse of every available piece of land. A geothermal heat pump air conditioning system can provide heating, cooling, and hot water for domestic use – one unit with three functions. For buildings that require both heating and cooling, ground-source heat pumps offer clear advantages. Baidu has an article that can be used for reference: http://wenku.baidu.com/view/eb4aaa6db84ae45c3b358c5a.html

This post was last edited by sailan on 2011-5-19 08:39. A geothermal heat pump is a technology that uses the underground soil layer as a cold (hot) source to provide heating, hot water, and air conditioning for buildings. The temperature beneath the strata remains relatively stable throughout the four seasons. In summer, the temperature underground is lower than that of the air at the surface, while in winter it is higher than the air temperature at the surface. A geothermal heat pump makes use of this property of the earth, exchanging heat with the soil or rock through heat exchangers buried underground. Geothermal heat pumps operate stably throughout the year; they can provide heating in winter and cooling in summer without the need for any additional heat sources or cooling equipment. Therefore, ground-source heat pumps are a new technology that is efficient, energy-saving, environmentally friendly, and conducive to sustainable development; they neither pollute groundwater nor cause land subsidence. In winter, the liquid inside the pipes draws heat from underground and transfers it into buildings through the system, while storing cold energy for use in summer ； In summer, heat is extracted from the building and discharged underground through the system, while heat is stored for use in winter. Geothermal heat pumps can reliably provide high-quality cooled and heated air throughout the year, creating a very comfortable indoor environment for us. Geothermal heat pumps are environmentally friendly and energy-efficient, making them highly valuable for widespread adoption.

Reply 1# sailan: Working principle of ground-source heat pumps: In nature, water always flows from higher places to lower places, and heat always moves from higher temperatures to lower temperatures. People can use pumps to draw water from lower places to higher ones, enabling the flow of water from low to high; similarly, heat pumps can transfer heat from lower temperatures to higher ones. Therefore, a heat pump is essentially a device for raising temperature. During operation, it consumes only a small amount of electrical energy, yet it is capable of extracting 4–7 times as much energy from the surrounding medium (water, air, soil, etc.) to raise the temperature for use; this is why heat pumps are energy-efficient. A geothermal heat pump is a type of heat pump that uses the earth or water as a heat source to provide heating in winter and cooling in summer for buildings; it merely \"transfers\" energy between the earth and the interior of the building. Use minimal electricity to maintain the desired temperature inside. In winter, 1 kilowatt of electricity delivers 4-5 kilowatts of heat from the soil or water sources into the indoor space. In summer, the process is reversed: the heat inside the building is transferred by a heat pump to the soil or water, thereby providing cool air inside the building. The energy obtained underground will be utilized in winter. This repeats over and over, integrating architectural spaces with nature. Obtained the most comfortable living environment at the lowest possible price. Principle of heat pumps: A heat pump system consists mainly of four components: a compressor, a condenser, an evaporator, and an expansion valve. By allowing the liquid working fluid (refrigerant or coolant) to go through a continuous thermal cycle of evaporation (absorbing heat from the environment) → compression → condensation (releasing heat) → throttling → re-evaporation, heat from the environment is transferred into the water. Compressor: It functions to compress and transport the working fluid from low temperature and low pressure to high temperature and high pressure, and it is the heart of a heat pump (refrigeration) system ； Evaporator: It is a device that generates cold energy; its function is to evaporate the refrigerant liquid that flows in through the throttle valve, thereby absorbing heat from the object to be cooled and achieving cooling effects ； Condenser: It is a device that releases heat; the heat absorbed from the evaporator, along with the heat generated by the work consumed by the compressor, is carried away by the cooling medium in the condenser, thereby achieving the purpose of heating ； Expansion Valve or Throttle: It functions to throttle and reduce the pressure of the circulating fluid, while also regulating the flow rate of this fluid entering the evaporator. According to the second law of thermodynamics, the work (electrical energy) consumed by the compressor serves to compensate for this process, enabling the working fluid to continuously absorb heat from low-temperature environments and release heat into high-temperature environments, thus enabling a continuous cycle. This is the principle behind ground-source heat pumps: Ground-source heat pumps utilize water and geothermal energy (groundwater, soil, or surface water) for heat exchange, with these sources serving as the means of providing cooling or heating. In winter, the heat stored in the geothermal energy is extracted to supply heating to indoor spaces; at this time, the geothermal energy acts as a \"heat source\"” ； In summer, the heat inside a building is removed and released into groundwater, soil, or surface water; at this time, the ground acts as a \"cold source\". http://www.jswjxd.com/admin/WebEditor/uploadfile/Image/20100729162010377.jpg

The use of geothermal energy is very common in the United States, and heat pumps are also widely used on China’s Qinghai-Tibet Railway. As is well known, in the Tibet region, the permafrost thaws when temperatures are high at midday in summer, causing the ground to become soft; (during winter nights, when temperatures are extremely low, this affects the lifespan of railway tracks), which poses risks to train operations. However, at depths of about 5–15 meters, the temperature remains very stable. The function of a heat pump is to maintain a stable temperature around the railway. Currently, heat pumps that use liquid ammonia as a heat transfer medium are in use; they are buried about 5 meters underground and 2 meters above the ground, with intervals of several dozen meters between them. In fact, by encouraging the use of heat pumps in buildings, it represents a one-time investment that is energy-saving and environmentally friendly. But more effort needs to be put into research and technology.