KR20110022334A - Hybrid type drying machine for agricultural and marine products - Google Patents

Abstract

PURPOSE: A hybrid-type agricultural and marine product drier is provided to improve the dried quality of agricultural and marine products by effectively and rapidly drying the agricultural and marine products. CONSTITUTION: A hybrid-type agricultural and marine product drier comprises the following: two thermal-cycling control chambers including two drying chambers(A,B) for stacking objects to be dried, a circulation fan, a heat-exchanger, and an auxiliary heater; an evaporator and a condenser; a heat pump and a heat pump connection pipe for controlling the temperature of the drying chambers; a drainage line for discharging condensed water; and a stirring apparatus heat-exchanging the two drying chambers.

Description

HYBRID TYPE DRYING MACHINE FOR AGRICULTURAL AND MARINE PRODUCTS}

The present invention relates to a hybrid agricultural and marine product dryer, and more particularly, to a hybrid agricultural and marine product dryer which can efficiently and quickly dry agricultural and marine products to improve dry quality of dry agricultural products and at the same time save energy.

In general, agricultural products produced in nature or products made in industrial processes inevitably contain a certain amount of water, and it is called drying to reduce the moisture content by controlling the water content in a good condition to use it.

In other words, the substance is changed into gas, liquid, and solid depending on the temperature, and the contained moisture is changed from the liquid state to the gaseous state and discharged to the outside air, which is called drying. Refers to reducing the moisture content of the tissue by discharging the moisture into the air.

In particular, agricultural and marine products are widely used for the purpose of long-term storage and transportation, and in the past, most of the natural drying using solar heat and wind, but artificial dryers such as hot air, steam, artificial light, etc. are the mainstream.

The temperature change with time of drying the agricultural and marine products is a graph as shown in FIG.

In general, the dryer is a process equipment that consumes a lot of energy due to the nature of drying, and the industrial equipment is expected to have very high energy saving expectations. The energy cost of drying in Korea consumes enormous energy amounting to about 300 billion of duty-free oil. have. This excessive energy consumption has greatly affected agricultural and fishery productivity due to rising energy costs in the era of high oil prices, causing environmental problems such as reduced profits and air pollution from fossil energy use.

The dry products of agricultural and marine products vary in dryness according to moisture content, epidermal condition, and availability. The principles, characteristics, advantages, and disadvantages of general-purpose dryers used for such drying are shown in Table 1 below.

As shown in Table 1, the conventional universal dryer has a significant change in drying efficiency due to excessive energy loss due to the reheating of cold air supplied from the outside during dehumidification, and the temperature and humidity of the surrounding air. There was a problem of lowering the merchandise such as nutrient destruction.

In addition, it takes a lot of drying time, there is a problem that it is difficult to achieve the purpose of drying when the outside temperature is low.

In addition, there was a problem that the price is high and the price rises toward medium and large.

In addition, if the microwave irradiation period is long, there is a problem that the temperature is high, there is a risk of quality damage, uniform drying is difficult, expensive equipment cost more than several hundred kW class.

<Table 1 Types of General Purpose Dryers, Their Principles, Features, Disadvantages and Advantages>

Drying method Principles and Features Advantages Disadvantages
sirocco
dryer
The structure of the box type is widely used, and consists of a hot air generating unit, a drying unit, and a control unit. The hot air heated indirectly by a burner and a heat exchanger is forced into the drying room, and the hot air is recycled or discharged after passing through the building. For drying by exhausting outside the drying chamber.

It can produce agricultural products with higher commodity value than sun drying.
Excessive energy loss due to the reheating of cold air supplied from the outside during ventilation and the change of drying efficiency due to the temperature and humidity of the surrounding air are severe, degrading the merchandise such as color and nutrient destruction of the dried product.
Dehumidification
dryer
It is a method to increase the drying speed by lowering the relative humidity of dry air to below the equilibrium relative humidity of the dry matter. It is heated by using a heat pump and dehumidified by high moisture heating air to reuse.

It is possible to dry at low temperature, thereby improving the quality of agricultural products without being affected by high temperature during drying. In addition, there is no environmental pollution using electricity.
It takes a lot of drying time.
Low outdoor temperature makes it difficult to achieve drying purpose
Far Infrared
dryer
Far-infrared rays are irradiated to dry matter in the drying box of the drying room by heat-infrared radiation heat transfer method of wavelength 5.6㎛ or more.

Drying time is shortened, drying energy is saved and uniform drying is possible.
The price is high, and the price increases as the size increases.
microwave
dryer
It is a method that can heat in a short time because it heats the surface and inside at the same time by heat-drying the produce by using the principle of microwave oven.

Reduction of drying time
Long microwave irradiation results in high temperature and risk of quality damage.
Uniform drying is difficult and equipment cost is high at hundreds of kW or more

In order to overcome this problem, the method of reducing the drying cost by applying a heat pump to the conventional general-purpose dryer, a closed air circulation was devised.

Conventional heat pump drying system is an integrated type in which two condensers (evaporators) are attached to one evaporator inside and one outside of the dryer. When dehumidifying and cooling, an external condenser operates and an indoor condenser operates. It is a system that absorbs heat.

Principles, features, advantages, and disadvantages of the dryers using these conventional heat pumps are shown in Table 2 below.

However, conventional heat pump dryers that use air as a heat source are sensitive to outside temperature and humidity, and direct use of variable air as a heat source makes it difficult to control a constant temperature, which reduces efficiency and deteriorates the quality of agricultural and aquatic product dry products. It may also occur.

Such a system is sensitive to ambient temperature, which dramatically reduces performance when the ambient temperature is low, and the heating temperature is lower than that required for drying. Heat pump type dryers are not applicable when high temperatures are initially required depending on the physical characteristics of the dry items, and the drying time is excessively increased, leading to deterioration of the dry product quality.

In addition, the conventional heat pump dryer is limited in temperature that can be used according to the heat source temperature in the evaporator, the heat pump operation itself is impossible because the high pressure in the cycle is impossible to cool the evaporator when the temperature in the dryer is above 40 ℃. Beyond the compressor maximum load, it is a factor to reduce the durability of the compressor.

<Table 2 Principles, Features, Disadvantages and Advantages of Existing Heat Pump Dryers>

division Dehumidifying dryer Aeration dryer




Cycle schematic

Principles and Features
-Heat pump, heating dehumidification, closed circuit, outdoor heat source
-Dehumidification through the condenser and warming, evaporator

-Heat pump and heating source
-Use of outside temperature and internal heat source
-Heat drying when the outside temperature is low
-Dehumidification in case of high outside temperature and high humidity
Advantages
-Low temperature drying
-The commercial property of the building is relatively high.

-Drying medium temperature (40 ℃) as heat source
-Heat pump, heat source supply equipment
Disadvantages
-Long drying time due to low temperature circulation
-Precise control of temperature and humidity is impossible
-Can not be dried at low outside temperature
Excessive dry energy costs

-Shorter drying time than dehumidification
-Control of drying quality due to outside air
-Can not use around 50 ℃ of drying temperature
Excessive dry energy costs

Therefore, the object of the present invention to improve the drying efficiency of 30 ~ 50% or more than the existing heat pump dryer currently used in most of the present, to solve the above problems, to reduce more than 100 billion won through energy saving, It aims to provide a highly efficient hybrid agricultural and marine products dryer that generates about 12 billion won in import reduction effect by reducing greenhouse gas of 1 million tons of carbon dioxide per year.

Hybrid agricultural and marine products dryer according to the present invention comprises two drying chambers for loading the dry matter; Two thermal alternating control chambers each having a circulation fan, a heat exchanger, and an auxiliary heater, and alternating heat of the two drying chambers; A heat pump and a heat pump connection pipe each having an evaporator and a condenser and controlling the temperatures of the two drying chambers; A drain line connected to the heat pump to discharge condensate; Characterized in that it consists of a stirring device for mutual heat exchange between the dry air of the two drying chambers.

In addition, the alternator includes a stirring fan capable of mixing the heating air and cooling air between the two drying chambers at a predetermined ratio; It characterized in that it consists of an electric switching gate and an electric damper for intermittent movement of air between the two drying chambers.

In addition, the dryer, characterized in that the simultaneous implementation of the heating COP (Coefficient of Performance) in the condenser and the dehumidification COP in the evaporator.

As described above, the hybrid agricultural and marine products dryer according to the present invention has the effect of maximizing farm income by shortening the energy saving and drying time and improving the drying quality of agricultural and marine products through the diffusion of high efficiency dry. In addition, there is an advantage to contribute to the prevention of environmental pollution, such as the reduction of fossil energy use and the reduction of greenhouse gas and environmental pollutant emissions due to energy saving.

In addition, there is an advantage of reducing the duty-free oil, increase the tax revenue, and the substitution of crude oil imports according to the diffusion of high-efficiency dryer.

Hereinafter, a hybrid agricultural product dryer according to the present invention will be described in detail with reference to the drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. In addition, terms to be described below are terms defined in consideration of functions in the present invention, which may vary according to a client's or operator's intention or custom. Therefore, the definition should be based on the contents throughout this specification.

In general, the function of agricultural and biological tissue changes is temperature and time. Therefore, if the skin is kept in a certain time by raising the temperature to the extent that the skin of the dried object is not disturbed and then maintained for a predetermined time, and then drying the process repeatedly to decrease the temperature, dehumidification and drying can be performed simultaneously in the same dryer, thereby saving energy.

In the ideal gas law (boile-char law), the gas pressure in the vessel increases in pressure as the temperature rises and drops as the temperature decreases. When the internal temperature of the building is higher than the outside temperature, the internal pressure of the building is High and low external air pressure. At this time, the difference in the partial pressure of the water vapor inside and outside of the dried object is greatly generated, and the water movement to the outside occurs rapidly, and the drying speed is several times faster.

Hybrid agricultural and marine product dryers use this technology principle and dry by repeating the cooling and dehumidification through the evaporator of the heat pump and the heating process through the condenser.

Hybrid agricultural and marine product dryers are a system that can consistently implement heating and cooling dehumidification in combination with some heating source in a closed loop structure, and has advantages such as shortening drying time, reducing drying cost, and improving dry quality.

The hybrid agricultural and marine product dryer of the present invention, as shown in Figure 2, each of the drying chamber (A, B) for loading the agricultural and marine products to be dried, and each of the thermal alternating control chamber provided with a circulation fan, a heat exchanger, an auxiliary heater and And a heat pump and a heat pump connecting pipe, a stirring device for mutually heat-exchanging each drying chamber drying air, and a drain line for discharging condensate.

The stirring device includes a stirring fan capable of mixing the heating air and the cooling air between the drying chambers at a predetermined ratio, and an electric switching gate and an electric damper for controlling the movement of air between the drying chambers.

The auxiliary heater may be composed of an electric heater or a burner, the auxiliary heater is used in the steaming section to operate the smooth to dry the tissue of the dry matter in the early stage of drying of the agricultural and aquatic products. In addition, the temperature of the evaporator side drying chamber is compensated when the evaporator side temperature falls below a certain temperature during the operation of the heat pump and the stable operation of the heat pump is disturbed.

The heat pump is operated through a Carnot cycle of compression → condensation → expansion → evaporation. FIG. 3 shows a ph diagram of the heat pump. The refrigerant introduced from the evaporator outlet compresses the low temperature low pressure refrigerant to high temperature and high pressure through the compressor. (① → ② process), the high temperature and high pressure refrigerant passes through the condenser and condenses to the supercooling area (② → ③ process). At this time, the condensation energy warms the dry matter in the drying chamber on one side and expands to low temperature and low pressure (③ → ④ process) flows into the evaporator, where the evaporator forms a dehumidification process (④ → ①) through the evaporation process in one drying chamber. The alternating heat pump alternates the refrigerant flows of the two drying chambers through the four-way valve to the reversible so that the heating chamber and the dehumidification are alternately controlled.

Figure 4 shows the safe operating area of the heat pump, the heat pump should ensure the operation of the safe operating area, which is affected by the design factors such as compressor, condenser, evaporator, expansion valve and the temperature and humidity of the operating area do.

The hybrid agricultural and marine product dryer of the present invention can maximize energy efficiency through the cooling / warming alternating operation of the heat pump, and simultaneously realizes “heating COP in condenser” + “dehumidification COP in evaporator” to simultaneously improve energy efficiency as well as drying time. Maintaining shortening and constant drying environmental conditions can lead to improved drying quality of the building.

Hereinafter, an embodiment of the present invention will be described with respect to an example in which the present invention hybrid agricultural product dryer is applied to red pepper drying.

Initially, the red pepper structure is relieved by steaming using a heater, followed by drying by repeatedly heating and dehumidifying through a heat pump and a temperature control chamber.

At this time, the heat pump is controlled within 50 ℃ during heating for optimum efficiency and stability.

Figure 5 shows the temperature and humidity of the drying chamber, respectively, in the initial steaming stage was maintained at 60 ~ 65 ℃ for 6 hours at this time the relative humidity was kept close to 100%. After the steaming step, the process of moisture absorption was carried out for 30 minutes, and after the moisture absorption, the hybrid operation of the agricultural and marine products dryer was started.

The alternating operation was tested by alternately heating and dehumidifying each drying chamber by switching the circulation direction of the refrigerant to the four-way valve of the heat pump. As the air flow in the drying chamber alternates with the alternating ducts, the relative humidity lowered when warmed enters the chamber of the low temperature dehumidification process, and the relative humidity increases by 95% or more. Chamber air is transferred to the chamber during warming and lowers relative humidity. It can be seen that the relative humidity in each drying chamber gradually decreases as the heating and dehumidification of the heat pump is repeatedly operated, and the drying is completed when the relative humidity in the dehumidification chamber is 55% or less. The temperature difference between the air temperature supplied to the drying chamber and the inside of the pepper indicates that the temperature deviation of about 4 ° C. was maintained in all the processes of heating and dehumidification.

Figure 6 shows the energy consumption with time of the hybrid agricultural and marine product dryer when the moisture content within 15% when drying 540kg red pepper.

The power consumption increases rapidly during the initial boiling process (preheating section) and gradually increases proportionally in the operating section of the heat pump. The drying time of red pepper was about 1,800 minutes and the total dry energy consumption was 380kw / h.

7 is a result of measuring the mass change of the dry matter with drying time. In the initial boiling stage, the mass change of the dry matter was small, and the mass reduction rapidly progressed as the heat pump was started to operate alternately, and then the mass decrease gradually occurred after 1,300 minutes of the drying reduction ratio.

As described above, the present invention has a temperature and humidity time function of the change of agricultural and aquatic organisms, and has a drying chamber within the closed circuit structure so that the temperature of the dry matter is not disturbed, and the temperature is increased by heating and cooling by dehumidification. By drying repeatedly, energy saving and drying quality can be improved.

Hybrid agricultural and marine product dryers combined with heat pumps and heat exchangers increase the relative humidity by smoothly performing the flow and alternating air through the warming / dehumidifying process in each chamber by optimizing the heat pump cycle under drying temperature and humidity conditions. The drying quality can be guaranteed and the drying time can be shortened through forced dehumidification to improve the drying quality and reduce the energy cost.

As described above, the present invention has been described based on the preferred embodiments, but these embodiments are intended to illustrate the present invention, not to limit the present invention, and those skilled in the art to which the present invention pertains without departing from the spirit of the present invention. Various changes, modifications, or adjustments to the embodiments will be possible. Therefore, the protection scope of the present invention should be construed as including all changes, modifications or adjustments belonging to the gist of the technical idea of the present invention.

1 is a graph of temperature change with time of agricultural product drying.

2 is a schematic view of a hybrid agricultural and marine product dryer according to the present invention.

3 is a p-h diagram of a heat pump used in the dryer of FIG.

4 shows a safe operating area of the compressor used in the dryer of FIG.

5 is a view illustrating a dry driving pattern of the dryer of FIG. 2.

6 is a graph of power consumption according to the time of operation of the dryer of Figure 2;

7 is a graph of the mass change of the dry matter with time during operation of the dryer of FIG.

Claims (3)

Two drying chambers for loading the dry items; Two thermal alternating control chambers each having a circulation fan, a heat exchanger, and an auxiliary heater, and alternating heat of the two drying chambers; A heat pump and a heat pump connection pipe each having an evaporator and a condenser and controlling the temperatures of the two drying chambers; A drain line connected to the heat pump to discharge condensate; Hybrid agricultural and marine products dryer, characterized in that consisting of a stirring device for mutual heat exchange of the drying air of the two drying chambers. According to claim 1, wherein the alternating device, the stirring fan capable of mixing the heating air and cooling air between the two drying chambers at a predetermined ratio; Hybrid agricultural and marine products dryer comprising an electric switching gate and an electric damper for intermittent movement of air between the two drying chambers. The hybrid agricultural / dryer product according to claim 1, wherein the dryer implements a heated COP (Coefficient of Performance) in the condenser and a dehumidification COP in the evaporator.

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