Heat recovery technology is a relatively mature and advanced energy-saving and environmentally friendly technology in the field of HVAC. It can recover waste heat to the maximum extent, save power consumption of the unit, provide free domestic hot water, and directly reduce waste heat emissions to the atmosphere. , especially for the southern region, has good economics. Now Tsinghua Tongfang has successfully applied heat recovery technology to air source heat pump units and water-cooled chillers.
Most of the water source heat pump units produced and sold at home and abroad today are dry systems and flooded systems. The energy efficiency of the dry system is relatively low, while the flooded system has disadvantages such as difficulty in liquid level control and oil return. The falling film system combines the advantages of dry and flooded systems. It not only achieves high efficiency, but also applies a new pressure differential oil return method to make it more stable and reliable. Falling film full heat recovery water source heat pump technology uses a falling film evaporator to achieve efficient operation. Compared with a flooded unit, it requires less refrigerant charging and has less impact on the environment; it uses a double-tube bundle shell-tube condensation The device realizes cooling and at the same time recovers and utilizes condensation waste heat to provide domestic hot water. The traditional approach is to use dual heat exchangers to work in series and parallel, or to implement it in an engineering system. The dual heat exchanger system has complex control and poor reliability; the grade of hot water recovered by the engineering system is low. The double-tube bundle heat exchanger used in this project to achieve heat recovery has overcome the above disadvantages.
The double-tube bundle shell-and-tube condenser is used to ensure that the cooling water and the recovered domestic hot water can operate independently, switch freely and not pollute each other, perfectly realizing the full heat recovery function.
The falling film evaporator is used to improve the operating efficiency of the unit and improve the maintenance performance. The refrigeration performance coefficient (energy efficiency ratio) is improved; the heat transfer performance of the evaporator is improved, and the material cost is reduced; the heat transfer temperature difference of the falling film evaporator is small, and the temperature difference of the water can be appropriately increased, thus reducing the use of groundwater flow and Water pump power consumption. Easy maintenance: The refrigerant water flows in the tube, and the dirt on the water side can be cleaned by opening the end cover; the refrigerant filling amount is small, which is more in line with environmental protection requirements.
The intermittent pressure difference oil return scheme is adopted, which is simple and reliable in operation. New pressure difference oil return scheme: When collecting oil, the high-pressure solenoid valve is closed, the pressure balance solenoid valve is opened, and the oil flows from the evaporator to the oil collector through the one-way valve. When oil is returned, the pressure balance solenoid valve is closed and the high-pressure solenoid valve is opened, using high pressure to press the oil back to the compressor. The time relay controls the action of the solenoid valve to achieve intermittent oil return.
According to Hefei General Mechanical and Electrical Products Testing Institute, Tongfang Renhuan’s falling film type full heat recovery water source heat pump unit has a measured nominal cooling energy efficiency ratio of 5.97, which is 30% higher than the national standard (≥4.60); The comprehensive energy efficiency ratio during refrigeration heat recovery operation (comprehensive energy efficiency ratio definition: the ratio of the sum of cooling capacity and heating capacity to the same power) reaches 7.09; the nominal heating energy efficiency ratio reaches 4.72, which is 31% higher than the national standard (≥3.60). At the same time, the performance of the unit has reached the requirements for energy-saving units in the "Technical Requirements for Certification of Energy-Saving Products for Water Source Heat Pump Units" stipulated by the "Bid Winning Certification Center". At the same time, it has reached the key technical parameters of the "Water Source Heat Pump Unit during the Eleventh Five-Year Plan" proposed by the National Development and Reform Commission. The unit's The performance has reached world-class level. Today, this technology has applied for a national patent. The successful research and development of this technology is in line with the development trend of "energy saving and environmental protection" in the world's air conditioning field, and is also in line with the national call for energy conservation and emission reduction. It has high economic benefits and far-reaching social benefits. Ground source heat pump is an environmentally friendly air-conditioning system that uses shallow underground geothermal resources that can provide both heating and cooling. It is a cost-effective energy-saving technology that uses renewable energy. Based on the current situation, the company decided to develop an efficient, environmentally friendly, and Energy-saving and reliable "high-efficiency flooded ground source heat pump unit"
Tongfang Renhuan optimized the design of the unit according to ground source working conditions, using flooded evaporation and economizer circulation system technology to improve the unit Energy efficiency. According to the overall process structure layout of the unit, a secondary external (or built-in) oil separator is installed, which not only improves the oil separation effect, but also reduces the resistance loss during the oil separation process. By setting up an oil collection tank in the evaporator, the lubricating oil is led back to the compressor using the pressure difference principle to achieve continuous oil return. By controlling the superheat of the evaporator return air and the electronic expansion valve, precise control of the liquid supply volume and liquid level is achieved, allowing the system to operate stably and efficiently. Through the design of the gas collection device in the evaporator, the air flow on the evaporation liquid level is uniform and the evaporation pressure is balanced, which further stabilizes the liquid level in the evaporator and also contributes to the stable operation of the system. The integrated application of these technologies in a flooded ground source heat pump unit system has not been reported at home or abroad.
According to Hefei General Mechanical and Electrical Products Testing Institute, Tongfang Renhuan’s high-efficiency flooded ground source heat pump unit has a measured nominal cooling energy efficiency ratio of 5.66, which is 29% higher than the national standard (≥4.40); nominal The heating energy efficiency ratio reaches 3.24, which is 4.5% higher than the national standard (≥3.10). The refrigeration performance indicators have reached the key research goals of the "National 11th Five-Year Plan".
The development of high-energy-efficiency ground-source heat pump products will help develop my country's environmental protection and energy conservation undertakings, especially in the fields of building energy conservation and emission reduction and pollution control, and will play a strong role in promoting it. This product meets the country's requirements for building a circular economy and building a conservation-oriented society, and is an effective way to utilize renewable energy on a large scale. The industrialization of this product will generate new profit growth points for our company itself and achieve a substantial increase in operating income. The promotion of this technology will surely drive the development of the entire refrigeration and air-conditioning industry and contribute to my country's social and economic construction. A heat pump is a device that can obtain low-grade heat from natural air, water or soil, and output usable high-grade heat energy through electricity. It can convert the consumed electricity into 3 times or even more than 3 times the heat energy. It is a A high-efficiency energy supply technology. The application of heat pump technology in the field of air conditioning can be divided into three categories: air source heat pumps, water source heat pumps and ground source heat pumps. Because heat pumps extract energy from nature, they are highly efficient and do not emit any pollutants. They are the cleanest and most economical energy method today. Today, with increasingly scarce resources, heat pump technology, as the most advanced way for humans to utilize low-temperature thermal energy, has received widespread attention and importance around the world.
Tsinghua Tongfang is the first domestic enterprise to apply heat pump technology to the field of air conditioning. With its mature technology research and development capabilities in this field, it has developed air source heat pumps, water source heat pumps, ground source heat pumps, heat pump water heaters, etc. It has four major series of heat pump products, deepens the technology and types of products according to different regional climate conditions and resource conditions, and has obtained more than 100 patented technologies. Tsinghua Tongfang has become a leader in the field of heat pump central air conditioning. Air source heat pumps use the infinite energy contained in the air to flow indoor heat to the higher-temperature outdoors in summer to keep the room cooler; in winter, the heat in the outdoor air can be used for heating to keep the room warm. Since the real cooling and heating heat of this kind of central air conditioner comes from the outdoor air, it does not require a cooling water system during cooling in summer, so the operating cost is very economical, and it can also save a lot of water resources. At the same time, no pollutants are produced when the system is working. It is very in line with my country's energy conservation and environmental protection trends and policies.
However, for a long time, ordinary air source heat pump central air conditioners can only be used in the middle and lower reaches of the Yangtze River, southwest and southern China, and cannot work normally in the northern region in winter. In 1996, Tsinghua Tongfang made technical improvements to the first-generation air source heat pump. The unit's unique "supercooling and ice suppression" technology effectively solved the problem of incomplete defrosting, allowing it to operate in the Yangtze River Basin and Yellow River where the lowest temperature in winter is -8°C. Used successfully in watershed areas.
After five years of painstaking research, Tsinghua Tongfang maximized the potential of the heat pump system and once again launched the world's only low-temperature air source heat pump unit that can achieve -22°C heating. The air source heat pump broke through the restrictions and was applied to North China for the first time. , completely changed the long history of using coal and gas for heating in the northern region, and played a positive role in improving the environment and saving energy.