Heat pump principle and application

First, the introduction of the principle of heat pump and energy conversion analysis The so-called heat pump, is a use of artificial technology to convert low-temperature thermal energy into high-temperature thermal energy to achieve heating effect of the mechanical device. The heat pump absorbs heat energy from a low-temperature heat source (such as ambient natural air, groundwater, river water, seawater, sewage, etc.), and then is converted into a warmer heat source and released into a desired space (or other area). This device can be used as a heating heating device, but also can be used as cooling and cooling equipment, so as to achieve the purpose of a dual purpose machine. .

The energy conversion of a heat pump unit is based on the use of its compressor, by consuming a certain amount of auxiliary energy (such as electrical energy), under the combined action of the refrigerant circulating in the compressor and the heat exchange system, from the environment heat source (such as water, air) It absorbs lower temperature heat energy, and then converts it into higher temperature heat energy and releases it into circulating medium (such as water, air) to become a high temperature heat source output. Here, the electrical energy is consumed due to the operation of the compressor, and the operation of the compressor causes the continuously changing refrigerant to generate different states of change and different effects (ie, evaporation and condensation and heat release) in different systems. The purpose and purpose of the recovery of low temperature heat source for high temperature heat source.

Second, the development of heat pump and application in China The first heat pump unit in Europe was manufactured in 1938. It uses the low temperature heat source of the river to supply heat to the city hall. The hot water output can reach 60oC. In the winter, heat pumps are used for heating and in the summer it can also be used for cooling. The promotion of the energy crisis in 1973 made the development of heat pumps a climax. At present, Europe's heat pump theory and technology are highly developed. This kind of "two birds with one stone" and environmental protection equipment have been widely used in France, Germany, Japan, and the United States.

Since the 1980s, there have been many developments in the application of heat pumps in various fields in China. In view of the relatively abundant geothermal resources in China, if the underground hot water that is used directly or after it has been cooled is used as a low-grade heat source for a heat pump, the temperature difference in the use of groundwater can be increased, and the utilization rate of geothermal heat can be increased. This is in Beijing and Tianjin. Areas have already had practical applications. This kind of equipment also proposes an effective solution to the current situation that China's energy efficiency is not high and distribution is uneven.

Third, the technical analysis of the heat pump:

1. The heat pump unit can achieve the effect of one machine for two purposes, that is, using heat pump heating in winter and cooling in summer. This not only saves the cost of the refrigeration unit, but also saves the floor space of the boiler room, while achieving environmental protection.

2. If the owner has a geothermal well, the heat pump device can be used for step conversion, which can greatly facilitate the full and effective use of thermal resources.

3. For energy consumption such as heating for living and domestic water heating, if direct heating is used to cause energy to be wasted, it is not desirable. The use of heat pump heating and heating can make more efficient use of electric energy.

4. The use of heat pump technology for heating heating does not cause any pollution to the atmosphere and the environment, and it is highly efficient and energy-saving. It is a green environmental protection technology and device that complies with the current basic energy and environmental protection policies in China and plays an invisible role for users themselves.

IV. Economic Analysis of Heat Pump Heating The economic efficiency of heat pump is determined by many aspects. Compared with boiler room heating, it obviously has the following characteristics:

1. The operating surcharge is smaller because of:

(1) The heat pump device does not require fuel transportation fees and storage fees, slag discharge transportation fees, etc.;

(2) The overhaul period is long. Because the boiler equipment is in contact with the high-temperature flue gas, the components are easily damaged. However, the heat pump system has only two components moving and has little wear. Usually, no maintenance is required.

(3) Managers and labor intensity can be reduced and wages saved.

2. Operating direct costs (electricity fees) are generally larger than coal-fired boilers, which is the main expense for heat pumps.

3. The initial investment cost of the heat pump is often greater than the boiler room equipment (referred to simply for winter heating). Heating equipment with the same capacity is more expensive than boiler equipment. In addition, the initial investment and the scale of the equipment are also related to the investment in the civil engineering scale of the engine room.

Heat pump energy utilization analysis:

The differential temperature energy of groundwater is large, and it belongs to a low heat source. The heat pump can be used as a useful heat for life and production. The heat pump has an energy efficiency of more than 1 (1:3.2-5.4), and the use of energy is much better than other methods of heating.

Fifth, the relationship between heat pump and energy price Heat pump heating is more advanced than boiler heating. When the heat pump is heated with coal, gas, oil and other methods, a comprehensive comparison is made with the cost of heating 10000 kcal heat. We can inferred:

1. Heat pump unit: Set the COP of the heat pump (refer to the ratio of its heating capacity to the consumed electric energy, ie, the unit's performance coefficient) to 4, the power consumption is 2.91kW, if the average price of electricity is 0.5 yuan/kWh (Beijing Area), the electricity fee is: 2.91x0.5 Yuan = 1.75 Yuan 2. Coal: Coal produces about 70% of the heat, so the required fuel is 2.13kg. If the coal price is 0.35 yuan/kg, the cost is: 2.13x0.35 yuan = 0.75 yuan 3. With gas: Gas can produce about 75% of the heat, then the required amount of gas is 3.81m3. If the gas price is 0.8 yuan/m3, the cost is: 3.81x0.8 yuan = 3.05 yuan 4. Fuel: The fuel can produce about 80% of the heat, and the required amount of oil is 1.16kg. If the oil price is 2.4 yuan/kg, then the cost is: 1.16x2.4 yuan = 2.78 yuan It can be seen that heating with coal is the cheapest, and the most expensive gas. The use of heat pumps has a direct relationship between the cost of electricity and the price of electricity, and it depends on the price of other fuels compared to other heating methods.

However, with the further implementation and implementation of energy policy, in actual projects, although the heat pump heating operation cost rate is slightly higher than the direct cost of burning coal and the initial investment of the overall supporting project is slightly more, it has high energy utilization rate and environmental protection. Such characteristics, as long as the perfect system-related technology support, it has a very good value of widespread application.