Introduction

The heat pump is essentially a heat-lifting device. The high-temperature heat pump drying unit uses the inverse Carnot principle to extract heat from the surrounding environment and transfer it to the heated object (higher temperature object). Its working principle and refrigeration The same machine, all work in accordance with the reverse Carnot cycle, the only difference is the operating temperature range.

working principle

The high-temperature heat pump drying unit mainly consists of a finned evaporator (outer machine), a compressor, a finned condenser (internal machine) and an expansion valve, which continuously evaporate by allowing the working fluid to continuously absorb heat in the outdoor environment. ) → compression → condensation (heat release in the indoor drying room) → throttling → re-evaporation thermal cycle process, so that the heat in the external low temperature environment is transferred to the drying room, the refrigerant in the system under the action of the compressor The inner circulation flows. It completes the gaseous boosting process in the compressor (temperature up to 100 °C), it enters the internal machine to release high-temperature heat to heat the air in the drying room, while being cooled and converted into a liquid liquid, when it runs to the outside machine After that, the liquid rapidly absorbs the heat and evaporates again into a gaseous state, and the temperature can be lowered to -0 ° C to -10 ° C, at which time the air around the heat absorber continuously transfers heat to the refrigerant. The heating efficiency of the high-temperature heat pump drying unit is much higher than that of other heating equipment. It can be seen that using the high-temperature heat pump drying unit as a drying device can save energy, and at the same time reduce the emission of pollutants such as CO2, and achieve the effect of energy saving and emission reduction. .

Place of use

High-temperature heat pump drying unit is suitable for drying bedding of hotels, seafood, vegetable dehydration, AD black white fungus, melon seeds, peanuts, fruits and vegetables, meat products, casings, tobacco leaves, leather, mushrooms, alfalfa, dried fruits, mosquito coils, tributes Fragrance, cloth, clothing, grain and grain, noodles, yuba, fertilizer, medicine, Chinese herbal medicine, paper, wood, seed, sludge, gypsum, hardware products, metallurgical products, mining by-products, chemical products, flue gas desulfurization gypsum, clay Drying of pasture, flue-cured tobacco, pulverized coal, slime, lignite, etc. In terms of industrial hot water, it can also meet the constant temperature of electroplating bath in electroplating plant, the heating and heat preservation of high temperature hot water in slaughterhouse, the supply of high temperature hot water in star hotels and the supply of high temperature hot water in industrial enterprises.

Features

1, can achieve low temperature air closed cycle drying, material drying quality is good. By controlling the working condition of the device, the temperature of the hot dry air in the drying chamber is between 20 and 80 ° C, which can meet the high quality drying requirements of most heat sensitive materials; the closed cycle of the drying medium can avoid exchange with the outside air. It may contaminate the impurities of the material, which is especially important for food, medicine or biological products. In addition, when the material is sensitive to oxygen in the air (easy to oxidize or burn out), an inert medium can be used instead of air as a drying medium to achieve oxygen-free drying.

2, energy efficient. The heat of the heated air in the heat pump dryer mainly comes from the sensible heat and latent heat contained in the warm and humid air discharged from the drying chamber. The energy input needs only the power consumption of the heat pump compressor, and the heat pump can consume a small amount of work. Taking advantage of a large amount of heat, the heat pump drying device SMER (the amount of moisture in the wet material consumed per unit of energy consumed) is usually 1.0 to 4.0 kg/kWh, while the conventional convection dryer has a SMER value of about 0.2 to 0.6 kg/kWh.

3. Temperature and humidity control is convenient. When the material has high requirements on the temperature and humidity of the air entering the drying chamber (such as wood), the evaporation temperature and condensation temperature of the working medium in the evaporator and condenser can be adjusted to meet the material's texture and appearance. Claim.

4. Useful volatile components in recyclable materials. Some materials contain volatile components (such as aroma and other volatile components). When dried by a heat pump, in the drying chamber, volatile components and moisture are vaporized together into the air. The air containing volatile components passes through the evaporator. When it is cooled, the volatile components therein are also liquefied, discharged together with the condensed water, and the condensed water containing the volatile components is collected, and the useful volatile components are separated by an appropriate method.

5. Environmentally friendly. In the heat pump drying device, the drying medium is closed in circulation, and no material dust, volatile substances and odor are polluted by the dry exhaust gas to the environment; the waste heat in the drying chamber exhaust is directly recovered by the heat pump to heat the cold dry air, The unit's thermal pollution to the environment.

6, can achieve multi-function. The heat pump in the heat pump drying device also has a cooling function, which can realize the low-temperature processing (such as quick freezing, refrigerating) or preservation of various materials by using the cooling function in the season when the drying task is less, and can also expand the heating function of the heat pump in the cold. The season is for planting (such as greenhouses) or heating of the farm.

7. The heat pump dryer is suitable for a wide range of materials. Suitable dry materials are mainly a large class of materials with a temperature tolerance between 20 and 80 ° C in the drying process, or materials that can withstand higher temperatures but are more energy-efficient or safe to dry by heat pump. Materials that have been studied and applied, such as wood (such as oak), grains, seeds, edible fungi (such as mushrooms, fungus), medicinal materials (such as ginseng, etc.), seafood (such as fresh oysters, scallops, etc.), biologically active products ( Such as cells, enzymes, tea, paper, and so on.

8. Compared with other low temperature (into the drying room air temperature <40 °C) drying device (such as microwave drying, vacuum drying, freeze drying), the heat pump dryer device has obvious economy due to the initial initial investment and low operating cost. Sex. The equipment cost of the heat pump drying device is mainly the heat pump portion and the drying chamber portion, wherein the drying chamber portion has the same requirements as the ordinary convection drying chamber, and there is no special airtightness and pressure bearing requirement.

9. Compared with the ordinary drying device (air temperature of the drying chamber >40 °C), since the initial investment of the heat pump dryer is generally higher than that of the air electric heating device, gas or coal-fired hot blast stove, the initial investment of the drying device is generally higher than The common drying device and the heat pump dryer drying device have high energy efficiency and low operating cost, and their comprehensive economy still has certain advantages.

Technical prospects

The material drying process is a huge energy-consuming process. According to statistics, in most developed countries, the energy consumed for drying accounts for 7%-15% of the total energy consumption in the country, while the thermal efficiency is only 25%-50%. And most of the drying process, especially for heat sensitive materials (such as food and biological materials), will have an effect on its color, nutrition, flavor and texture. The heat pump drying technology has the advantages of low energy consumption, low environmental pollution, high drying quality and wide application range, and its excellent energy saving effect has been proved by various domestic and foreign experimental research institutes.