Air heat pump water heater

Air-energy heat pump water heaters are also called "air source heat pump water heaters," "heat pump water heaters," "air energy heaters," and so on. The heat pump in the air-energy heat pump water heater (air source heat pump water heater) can absorb the low-temperature heat energy in the air. After being compressed by the compressor, it transforms into high-temperature heat energy and heats the water temperature. This type of water heater (air source heat pump water heater) has the characteristics of high efficiency and energy saving, and the same amount of hot water is produced. The use cost of the air energy water heater is only 1/4 of the electric water heater, and 1/3 of the gas water heater is more than the electric assisted solar water heater. High energy efficiency.

working principle

Air-energy heat pump water heaters, also known as "air source water heaters," "heat pump water heaters," "air energy water heaters," and other air-energy heat pump water heaters essentially use the principle of refrigeration (reverse Carnot cycle principle), which obtains low-grade thermal energy from the surrounding environment. , After the power has been raised by the power, it is output to the condensation end, which produces equipment that can be used by people with higher quality heat energy.

A compression heat pump device, consisting of an evaporator, a compressor, a condenser, and an electronic expansion valve, is used to continuously perform evaporation (absorb heat in the environment) → compress → condense (discharge heat) → throttling → Re-evaporate the thermal cycle to transfer heat from the environment to the water.

When the heat pump is working, the energy QA stored in the environmental medium is absorbed in the evaporator; it itself consumes a part of the energy, that is, the compressor consumes power QB; the heat release QC is performed in the condenser through the working fluid system, QC=QA QB, it can be seen that the energy output by the heat pump is the work QB of the compressor and the heat QA absorbed by the heat pump from the environment; therefore, the use of heat pump technology can save a lot of energy, create the same amount of hot water, air energy The use cost of the water heater is only 1/4 of that of the electric water heater, and 1/3 of the gas water heater is higher than the energy-assisted solar water heater.

Heating method

The first generation of heating methods: direct thermal evaporator and condenser are in the host, cold water directly into the host, a one-time direct heating by the condenser to a preset temperature of 55 degrees, and then under the self-effect of cold water pressure, direct delivery Into the holding tank. The advantage is to maintain the water is 55 degrees hot water, energy-saving effect is good; the disadvantage is when the water temperature in the insulation tank drops, but also use the pump to pump back to the host heating or auxiliary heating.

The second generation of heating methods: circulating evaporator and condenser are in the host, but the cold water directly into the holding tank, and then pumped back to the host heating, must be a circulation pump, the heating method is layered Cyclic heating, because he is heating the water temperature to a preset temperature by multiple cycles. The advantage is that the energy efficiency is higher compared to the direct thermal type, because the closer the temperature is to the original temperature, the better the heat conduction effect and the higher the energy efficiency. The disadvantage is that it is necessary to use a circulating pump so that some electricity will be wasted, and the diameter of the hot water delivery will be longer, so the energy consumption will be more. The cold water enters the heat preservation tank from above, and the hot water is produced from below, and the general hot water is lighter than the cold water. The water in a container is usually hotter than the one below, so adding cold water above will cause the temperature of the outlet water not to be constant and will cause water to mix.

The third generation of heating methods: split direct thermal (also known as: rapid thermal type)

There is only an evaporator in the main unit. The condenser is in the holding tank. The cold water is injected from below. The hot water is discharged through the upward force of the cold water. Therefore, it is not necessary to have a circulation pump like the circulation machine, and the condenser is directly in the tank. The medium exchanges heat with water, so the heat exchange is direct and does not pass through any pipe diameter. As such, the energy efficiency and the heating speed must be higher than that of the cycle machine. Since the hot water is discharged from the above, the discharged hot water can be kept basically constant. [If it is necessary to use a circular type for special circumstances, then the size of the tank can be used to solve, so his other advantage is that it has strong variability.

Features

1, security: the use of heat in the air to heat the water temperature, water and electricity completely separated, and set up multiple protection, there is no security risk.

2, energy saving: use a small amount of electrical energy to heat the air to the water heating water, energy consumption is 1/5 of the electric water heater; gas water heater 1/6; fuel oil water heater 1/4; ordinary solar energy 2/3; And you can use low valley electricity to achieve more energy-efficient results.

3. It is not affected by the environment: It is an all-weather hot water supply system. Whether it is cloudy, rainy, spring, summer, autumn or winter, day or night, as long as there is hot water in the air, the low temperature heat energy of -10°C～30°C can be achieved. Through the role of the heat pump unit, hot water with a temperature of about 60°C is provided.

4. Intelligent: Automatic operation, no need to watch, comes with temperature control device and insulation layer, can automatically replenish water, heating, power, can provide hot water 24 hours, both hot water, air conditioning, heating multiple functions.

5.Easy installation: The air energy water heater occupies a small space and its appearance is similar to that of the air conditioner outdoor unit. It can be directly connected to the heat preservation water tank or connected with the heating pipe network. It is suitable for high-rise buildings in large and medium-sized cities. For large-scale central heating, it is the best choice. No solar collector board is needed, reducing the floor area by 95%. The use of solar water heating equipment can reduce the area of ​​solar collectors by 50%, save a lot of solar collector area, and reduce the volume of the hot water storage tank.

Advantages and disadvantages

After more than ten years of development, the air-source heat pump water heater industry has seen rapid development in the market for air-energy water heaters. Up to now, production companies have reached more than 500, and in June this year, they successfully completed the national energy-saving project, enjoying a subsidy of up to 600 yuan, further Promote the development of the industry. Heat pump water heater is an important component - refrigerant, which is directly related to the energy efficiency of the product. At present, the southern heat pump water heater refrigerant is mainly R22, R134a, and later there are some mixed refrigerant come out R415b, R417a, etc., different refrigerants have their advantages and disadvantages.

R22 is very suitable for air conditioning, because the condensing temperature can always be controlled below 45 degrees (since the air temperature is almost always below 40 degrees); but the heat pump water heater water temperature is always required above 40 degrees, when the condensation temperature is always above 45 degrees , R22 exhaust temperature easily exceed 85 degrees (oil easy cracking temperature), especially when the air temperature is above 40 degrees. Therefore, R22 is used in heat pump water heaters because the R22 exhaust temperature is high, resulting in poor cooling of the compressor lubricant and a sharp increase in the cracking speed, thereby shortening the life of the compressor. In addition, R22 has an ODP value of 0.05, which has a destructive effect on the ozone layer. However, according to the provisions of the “Montreal Protocol”, R407C and R410A have been used in place of R22 in Europe since 2004, while in Japan, all R410A refrigerants have been used, that is, in 1985. The production volume is based on the benchmark, which was compressed to 65% in 2003, 35% in 2010, and 10% in 2015. By 2030, developed countries will completely ban R22, and developing countries will also phase out R22 in 2040. According to the refrigerant replacement schedule, China must completely ban the production of refrigerant R22 products by 2040 at the latest.

R134a (CH2FCF3) is an environmentally friendly refrigerant and has a low exhaust gas temperature, but its boiling point (at normal atmospheric pressure) is -26.5 degrees. This causes the heat pump to become less efficient due to slow evaporation of refrigerant in the winter. Therefore, we see that The R134a is used for indoor refrigeration equipment, or in the tropics. Northern outdoor cooling equipment is not used (unless it is not used in winter).

R415b, a mixed refrigerant, was invented by Prof. Zhu Mingshan of Tsinghua University (member of the International Refrigeration, Air-Conditioning and Heat Pump Technical Committee of the UN Environment Program) International Refrigeration No.: R415A, R415B, R418A, R425A, and has been included in the National Key Environment Protection and practical technology (A) projects are promoted and used. Won the State Council "National Technology Invention Award", the State Environmental Protection Administration "National key environmental protection and practical technology Class A promotion project", and obtained the United States State Environmental Protection Administration "SNAP Plan" certification, has been widely used in Europe and the United States. Its ODP is not zero, and the exhaust temperature is slightly higher compared to 417a. After replacing R22 with R415b, the heating capacity of the system is reduced by approximately 10%.

R417a is a mixed refrigerant (HFC-143, HFC-125 and R600), which was first invented by Rhodia in 1997 (sold to DuPont in 2005 and headed by Li Bing). In Europe, it is mainly used to replace R22 (not environmentally friendly and (Energy-saving), which accounts for 80% of the market share of alternative refrigerants. According to the Montreal Treaty, China will start phasing out the R22 working medium on January 1, 2013. R417a is one of the alternatives. R417a features environmental protection, high efficiency and low exhaust temperatures. More suitable for heat pump water heaters, and now, domestic heat pump water heater manufacturers began to increase the scope of the use of refrigerants, domestic exports to Europe use more air conditioning R417a.

R417a has one drawback: With the replacement system, the system heating power is reduced by about 10%; that is, the capacity of 10 presses becomes about 9 horsepower. It can be seen from the inspection table provided by R417A inventor Rhodia that the same air conditioner uses R417A with an efficiency increase of 13% (3.00/2.65) over R22, which is an advantage. However, the heating capacity of the R22 is 3,548 watts (the heat pump water heater only requires heating). The heating power of the R417A is 3,149 watts, and the heat of the R417A is 10% lower than that of the R22. This is the unfavorable aspect of R417A when it is used for heating. It is necessary to increase the ratio of the press and heat exchanger to compensate for the attenuation.