1. Characteristics of heat pump yuba technology drying (1) Low energy consumption cost - The heat pump drying device can recover the sensible heat and latent heat of the hot and humid air during operation, and the energy is fully and reasonably utilized. It is a recognized high-efficiency energy-saving equipment. .
(2) No pollution to the environment - Since the whole process of heat pump drying is carried out in a closed system, it is not necessary to drain the surrounding environment, and at the same time, harmful and odorous gases are also discharged. If the inlet and outlet systems are all enclosed in the pipeline, the entire operation will be kept in a clean environment. This is a unique advantage compared to other drying methods.
(3) Good drying quality - the drying medium in the heat pump drying device is circulated in the closed space; it is not affected by external climatic conditions, and runs smoothly under the same conditions all year round, so the dry quality is good (4) indirect Closed heating, environmental protection and energy saving, reducing material loss.
(5) Investment province, small land occupation, less supporting civil works (6) Controllable dry moisture, minimum of 10% or less
2, the difference between heat pump drying and boiler steam drying
2.1 The working principle of the existing yuba baking room and the drying process analysis The yuba drying room relies on the internal heating elements to heat the outside air entering the drying room, and at the same time, rely on the motor to drive the fan impeller to rotate, so that the heated air Contact with wood, humidified and filtered out of the drying room.
The id diagram of the air circulation of the existing drying room 1. The ambient state air (point 1) enters the drying room.
2. Heat the air to state point 2 using a heating element. During this process, the air dry bulb temperature t increases, the absolute moisture content d does not change, and the relative humidity decreases.
3. The high temperature and low humidity air of the state point 2 flows through the dried article, and the moisture in the air is continuously diffused into the air because the partial pressure of the water vapor in the air is lower than the partial pressure of the water vapor on the surface of the laundry. For air, this process is an equal process. The dry bulb temperature of the air decreases, the absolute moisture content d and the relative humidity increase, reaching the state point 3;
4. The humid air in state point 3 is discharged outside the drying room.
2.2 The inadequacies of the existing Yuba boiler room drying room are as follows:
1. Energy consumption indicators are not ideal. First of all, for the new wind form, the exhaust air still contains a lot of heat energy, which will cause waste of energy. I. The existing drying room, whether electric heating or coal heating, is an energy conversion device, that is, moisture in the dried goods. The heat required for evaporation is completely converted from heat. At the working temperature of the drying room of 60 ° C, the latent heat of vaporization of the water is 2359 kJ / kg, that is, at least 2359 kJ of electricity is consumed by 1.kg of water in the evaporatively dried article. Regardless of factors such as fan, heat leakage, rotating moving parts, etc., the actual power consumption will be greater than this value. 2. The humid air after the drying room absorbs moisture is discharged into the room, which will further deteriorate the indoor air condition. In some types of drying rooms, the exhaust duct is used to discharge the air to the outside, but such a large area, affecting the interior beauty, and the installation and construction are relatively inconvenient.
3. Uneven heating, poor drying quality 4. Dehumidification is not ideal. Increase drying difficulty 5. Serious environmental pollution
2.3 The working principle of the heat pump drying room and the drying process analysis 1. The working principle of the heat pump drying room The heat pump is different from the boiler heating and energy conversion mode, and is an energy transfer device. Specifically, at the cost of consuming part of the energy, heat is extracted from the low-level heat source, and then the consumed energy is transferred to the high-level heat source together with the absorbed heat to achieve the purpose of heating. This work mode is more than the existing drying room. Energy saving.
Analysis of air treatment process in heat pump dryer and id diagram of air circulation in heat pump drying room
The drying room adopts a new style of wind-heating. The air in the heat pump-type drying room can realize circulating flow, and the working process can be represented as Figure 2 on the air i-d diagram. The specific analysis is as follows:
1) The humid air after absorbing the moisture of yuba is flown through the evaporator of the heat pump system to realize the cooling and dehumidifying process. That is, the dry bulb temperature I of the air is lowered, and the water vapor carried in the air condenses into water on the surface of the evaporator, and the absolute moisture content d decreases (process 3+1);
2) The air after cooling and dehumidification passes through the condenser to achieve isothermal temperature rise. That is: the dry bulb temperature t of the air rises, the absolute moisture content d does not change, and the relative humidity decreases (process 1-2);
3) The high-temperature and low-humidity air blown out by the condenser flows through the dried articles, and then returns to the evaporator after the humidification and temperature reduction (process 2-3), and the cycle is restarted.
2. Advantages of heat pump type drying room It can be seen from the above work process that drying with heat pump type drying room can overcome the defects of existing drying room, achieve energy saving, wide adaptability and environmental friendliness.
a) The heat pump is an energy transfer device that saves energy compared to existing drying rooms. According to conservative estimates, the energy efficiency ratio of the heat pump system is only 3.5, and it is necessary to provide 2359kJ of latent heat of vaporization, which only consumes 674kJ of electricity. If the power consumption caused by factors such as fan, heat leakage, and rotating moving parts is the same as that of the original dryer, the maximum power consumption is 674kJ, achieving 70% energy saving. If these factors are properly optimized, the energy saving effect is more obvious.
1) Since the absolute moisture content d of the air flowing through the condenser is small, the heat pump system can reduce the relative humidity of the air at a relatively low condensation temperature, thereby improving the moisture absorption capacity of the air, thereby facilitating the expansion of the heat pump drying room. The scope of the item.
2) There is no need to install an exhaust duct, nor will the hot humid air be discharged indoors, which will not affect the interior decoration and indoor air environment.
3) Uniform heat, good drying quality 4) Cold air removed by the heat pump main unit can solve the problem of summer cooling and save energy
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