CN104145826B - A kind of automatic control system of poultry house Wet-curtain temperature reducing in summer and control method thereof - Google Patents

Abstract

The invention relates to the technical field of cooling equipment, in particular to an automatic control system and a control method for cooling a wet curtain in livestock and poultry houses in summer. The object of the present invention is to provide an automatic control system and control method for cooling the livestock and poultry house in summer with the wet curtain, which can realize the cooling system of the cooling fan of the wet curtain fan to automatically control the temperature in the livestock and poultry house. When the present invention is used to transform the cooling system of the existing livestock and poultry house, it only needs to increase or change the position of the sensor and adjust the control system, without the need to modify the main structure of the livestock and poultry house. The transformation cost is low and the scalability is great.

Description

An automatic control system and control method for cooling down with wet curtains in livestock and poultry houses in summer

technical field

The invention relates to the technical field of cooling equipment, in particular to an automatic control system and a control method for cooling a wet curtain in livestock and poultry houses in summer.

Background technique

The general high temperature in summer in my country, especially the continuous high temperature and high humidity in the south of the Yangtze River, has a great impact on my country's house breeding industry. The high temperature in the house can cause heat stress to animals, which will change various physiological and biochemical reactions of animals, which will lead to serious problems such as decreased feed intake, decreased production performance, and decreased disease resistance of livestock and poultry. Events leading to mass deaths of livestock and poultry have also been reported from time to time. Excessive humidity in the house can exacerbate heat stress in animals. How to overcome the troubles caused by high temperature and minimize the unfavorable factors is an important problem that livestock and poultry producers need to solve.

The wet curtain fan cooling system is currently the most widely used environmental control technology for alleviating the heat stress of livestock and poultry housed in summer. When the outside air passes through the moistened wet curtain paper, the moisture evaporates in the air, absorbs the latent heat of evaporation from the air, and lowers the air temperature. The technology consists of negative pressure fan, wet curtain paper, water pump circulation system and control device.

The traditional "on-off" mode is currently the most common control method for evaporative cooling of wet curtains in my country. That is, when the temperature in the house reaches a certain level, when the manager thinks that the temperature in the livestock house is too high, the water pump will be turned on manually. The water is delivered to the top of the cooling pad paper, and then the cooling pad paper is wetted, and the system starts to cool down the house. When the temperature outside the house drops to a certain level in the afternoon, the manager thinks that the excess heat generated by the chickens in the house can be discharged only through ventilation without the cooling of the wet curtain, and the water pump is manually turned off. Some livestock and poultry farms install timers at the water pumps that supply water to the wet curtain paper. The timers can automatically turn on or off the water pumps according to the preset time. When the water pump is turned off, no matter how the outside temperature changes, the water pump will be turned on and off according to the preset time. This simple "on-off" control method has the following problems: ① When using this control method, once the water pump is started, it will not stop, the wet curtain paper will be completely wetted quickly, and the temperature in the house will drop rapidly. Studies have shown that in dry and hot areas, the temperature in the house drops sharply at the beginning of the start-up of the wet curtain cooling system, and in some areas it is as high as 10°C or even 15°C. Studies have shown that this sudden drop in temperature has adverse effects on the health of livestock and poultry, especially livestock and poultry near the wet curtain are prone to colds and other respiratory diseases. ②The manual opening or closing of the wet curtain is generally judged by the manager based on his own feeling or experience. Human feeling is different from that of animals, and there are great differences between different people's feelings. Therefore, this kind of control The method has great sensory and randomness, and it is difficult to provide a relatively stable and comfortable environment for animals. ③The water curtain system using timer switch has a certain degree of automation compared with the artificially opened or closed water curtain system, but the temperature changes every day. When the weather is hot, it may cause the water curtain to open The house is still at a higher temperature before or after closing, so that the animals are in a state of severe heat stress. ④Using this "on-off" controlled wet curtain cooling system, during the operation process, the water pump is always on to continuously supply water to the wet curtain paper, which will cause high humidity in the house. When the weather is sultry, the humidity in the larger house is unfavorable. For example, the animals dissipate heat through the evaporation of water vapor in the skin or respiratory tract, which will aggravate the heat stress of the animals and have adverse effects on the animals. ⑤Using this "on-off" controlled wet curtain cooling system, once the cooling system is started, the cooling degree will not be controlled by humans, but will be determined by the wet bulb temperature of the air on the day and the cooling efficiency of the wet curtain cooling system. Therefore, it cannot Adjustments are made to the desired temperature of the animal's growth, so fine-grained control of the environment is difficult. ⑥Using this method, it is difficult to realize the automation and real-time control of the environment.

In recent years, my country has introduced from abroad and independently developed the automatic environmental control system for livestock and poultry houses. The commonly used method is to set temperature and humidity sensors (inside the house, outside the house, etc.) in the system. The breeder can set the actual temperature required in production as the target temperature. When the temperature in the house exceeds the target temperature, the system will automatically Start the water pump to wet the wet curtain, and the temperature in the house begins to drop. When the temperature of the house is lower than the target temperature, the water pump stops supplying water, and the temperature of the house starts to rise. When the temperature of the house reaches the target temperature, the water pump starts again, and the temperature in the house starts to drop again. Repeat this to make the temperature in the house fluctuate around the target temperature. Compared with the "on-off" control mode, this method has many advantages, mainly as follows: ①The temperature and humidity sensor in the house can collect the temperature and humidity in the house in real time, and feed back to the control computer. The temperature and humidity conditions of the house can be controlled, and then the working status of the water pump and fan can be controlled, so that the temperature in the house can fluctuate around the target temperature. Therefore, producers can set the target temperature according to their own needs, so that the temperature in the house can be controlled near this target temperature. ②This control method solves the problem of sudden temperature drop in the early stage of wet curtain operation in the "on-off" control method, and effectively protects the health of livestock and poultry. ③ The number of fans that can be turned on can be adjusted in real time according to the temperature in the house. ④ Energy saving and water saving. ⑤ High degree of automation, which can realize fine control of the environment in the house. However, this control method also has many disadvantages, mainly in the following aspects: ①The system operation program is very complicated, and it is difficult to realize the good operation of the system if the relationship between the parameters is not clear. ②A lot of important parameters need to be input into the system by the manager himself, and whether the input of these parameters is reasonable or not directly affects the operation effect of the system. Take the cycle time setting of water pump opening and closing as an example. If the water pump opening time is set too short, the wetting area of the cooling pad will be small, and it will be difficult to reach the target temperature in the house. On the contrary, if the water pump is turned on for too long, it may cause a sudden drop in temperature at the initial stage of wet curtain operation or excessive humidity in the house, which will have adverse effects on animals. Even if the start time of the water pump is set well, the time when the water pump is turned off will have a certain impact on the operating effect of the system. For example, when the water pump is turned off for a short time, it will cause the water pump to start frequently, and if it is turned off for a long time, the temperature in the house may not be able to drop to the required temperature. The actual cooling effect that different water pump opening and closing cycles can achieve in production is also affected by the temperature and humidity outside the house and the number of fans in the house. ③The number of fans to be turned on in different temperature ranges and time periods needs to be set by the production manager. A small number of fans will lead to high temperatures in the house or a large temperature difference between the head and the tail. If too many fans are turned on, it will not only cause waste of power , It will also cause the wind speed passing through the cooling pad paper to be too high, and the air and the water on the cooling pad paper cannot conduct sufficient heat exchange, which will affect the cooling effect of the cooling pad cooling system. ④ This control system uses the average temperature in the house as the target temperature for cooling, and this temperature regulation method will inevitably cause some animals to be in a state of heat stress. ⑤ When using this control method, the position of the sensor should have a significant impact on the operation of the system. For example, if the sensor position is set unreasonably, the temperature and humidity collected by it cannot represent the actual average temperature in the house, which will affect performance of the entire system. The length, width, and height of different livestock and poultry houses are different, and the position of the sensor must be different. How to find a reasonable installation position is a difficult thing.

The external environment is changing all the time. Even if the livestock and poultry production managers have good environmental control qualities, they may not be able to control the environment in the house within a good range. In addition, there is a large difference in climate between the north and the south of my country, and the personnel engaged in related work lack environmental control technology and knowledge. The breeding environment control technology has become a major bottleneck restricting large-scale livestock and poultry breeding in my country.

Contents of the invention

In view of the above problems, the object of the present invention is to provide an automatic control system and control method for cooling the livestock and poultry house in summer, which can realize the cooling system of the wet curtain fan to automatically control the temperature in the livestock and poultry house.

In order to achieve the above object, the present invention provides the following technical solutions:

An automatic control system for the cooling of livestock and poultry houses with wet curtains in summer, wherein,

A plurality of wet curtain papers 1 are arranged on one side of the wall of the livestock and poultry house along the horizontal direction and a part of the wall connected with it along the longitudinal direction; on the opposite side of the wall, a plurality of negative pressure fans are arranged. 4. The wet curtain paper 1 is connected to the wet curtain water supply system, and the wet curtain water supply system includes a water pump 2, a circulating pool 3 and a water supply pipe;

Multiple rows of cages are arranged longitudinally in the livestock and poultry house, and passages are set between two adjacent rows of cages; in each row of cages, multiple sets of cages are set, among which the first set of cages near the end of the air inlet is the first rack 5 , the last group of cages is the tail frame 6; in the poultry house, a deflector 7 is set between the wet curtain 1 and the first frame 5, and the controller 8 is arranged in the work room outside the poultry house;

The first temperature and humidity sensor 9 is set outside the livestock and poultry house, a plurality of second temperature and humidity sensors 10 are set at a plurality of first frame 5 positions, and a plurality of third temperature and humidity sensors 11 are set at a plurality of tailstock 6 positions;

The first temperature and humidity sensor 9 , the second temperature and humidity sensor 10 and the third temperature and humidity sensor 11 are respectively connected to the controller 8 .

An air pressure sensor 12 is arranged outside the livestock and poultry house, and the air pressure sensor 12 is connected with the controller 8 .

The opening angle of the deflector 7 can be adjusted.

A control method for an automatic control system of a wet curtain cooling in livestock and poultry houses in summer, comprising the following steps:

1) According to the breed and the age of the animals raised in the house, select a suitable temperature T _a for raising in the house;

2) Determine the control mode of the wet curtain fan cooling system according to the determined temperature T _a ;

When t>T _a +Δt, the system enters the "on-off" wet curtain control mode; when t≤T _a +Δt, the system enters the intermittent wet curtain control mode;

Among them, t is the calculated temperature when the air enters the livestock and poultry house after being cooled by the wet curtain, and the unit is °C; The temperature difference when entering the livestock and poultry house, the unit is ℃;

3) When the system is in the "on-off" wet curtain control mode:

The started water pump 2 runs continuously until it is switched to the intermittent wet curtain control mode;

4) When the system is in intermittent wet curtain control mode:

①The temperature T1 and relative humidity at the _first rack 5 are collected in real time by the second temperature and humidity sensor 10 When the first frame 5 was installed with a plurality of second temperature and humidity sensors 10, the minimum value was used as the control parameter; the temperature _T and the relative humidity at the tailstock 6 places were collected in real time by the third temperature and humidity sensors 11 When the tailstock 6 is equipped with a plurality of third temperature and humidity sensors 11, the maximum value is taken as the regulation parameter, and ΔT is the difference between the temperature T _of the _tailstock 6 and the temperature T1 of the first frame 5, that is, the first frame 5 and the first frame 5. The temperature difference of the tailstock 6:

ΔT = _end of T - T ₁ ;

② When T ₁ ≤ T _a -ΔT, maintain the on-time of water pump 2; when T ₁ > T _a -ΔT, increase the on-time of water pump 2 and shorten the off-time of water pump 2; when the off-time of water pump 2 is shortened to 1 minute, If the water pump 2 is started for each cycle opening and closing time, the system will automatically enter the "on-off" wet curtain control mode;

③When the _end of T>T _a , increase the number of fans 4 turned on; when the _end of T≤T _a , keep the number of fans 4 turned on unchanged.

In said step 2),

$\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.2</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.8</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}^{<span\; class="notranslate">\; *</span>}$

$\mathrm{<span\; class="notranslate">\; \&Delta;t</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>$

Among them, n is 0.65～0.75; T _d is the air temperature outside the house, which is collected in real time by the first temperature and humidity sensor 9, and the unit is °C; is the wet-bulb temperature outside the livestock and poultry house under the actual atmospheric pressure, in °C;

in,

In the formula, _Tw is the wet bulb temperature outside the livestock and poultry house under standard atmospheric pressure, in °C; is the relative humidity, collected in real time by the first temperature and humidity sensor 9, expressed with a decimal point; ΔP is the difference between the standard atmospheric pressure and the actual atmospheric pressure; is Pa;

in,

Compared with prior art, the beneficial effect of the present invention is:

The invention effectively combines the traditional "on-off" cooling pad control mode with the intermittent cooling pad control mode, and automatically realizes the conversion of the two modes according to the external environment and the temperature environment required by livestock and poultry, and then realizes The wet curtain fan cooling system automatically controls the temperature; according to the different growth stages of the livestock and poultry in the livestock and poultry house, the suitable production temperature T _a of the corresponding stage can be determined, and the highest temperature in the house should not exceed T _a as the target temperature for regulation, which has changed the traditional The method of taking the average temperature in the house as the target temperature for regulation ensures that all animals in the livestock house are in a relatively comfortable temperature range; realizes the automatic control of the number of fans running, effectively avoiding the current intermittent wet curtain regulation Medium ventilation level setting; when using the present invention to transform the cooling system of the existing livestock and poultry house, only need to increase or change the position of the sensor and adjust the control system, without the need to modify the main structure of the livestock and poultry house, and the transformation cost is low , great scalability.

Description of drawings

Fig. 1 is the system component layout schematic diagram of the automatic control system of the wet curtain cooling of livestock and poultry house in summer of the present invention;

Figure 2 is a schematic diagram showing a stepwise increase in the ventilation volume in the livestock and poultry house with the number of ordinary fans turned on;

Figure 3 is a schematic diagram showing that the ventilation volume increases linearly with the number of fans turned on after the frequency conversion fan is combined with the ordinary fan;

Fig. 4 is a schematic diagram of the control mode of the present invention.

[Description of main component symbols]

1 wet curtain paper

2 water pumps

3 circulating pool

4 Negative pressure fan

5 first

6 tailstock

7 deflector

8 controllers

9 The first temperature and humidity sensor

10 Second temperature and humidity sensor

11 The third temperature and humidity sensor

12 Air pressure sensor

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

As shown in FIG. 1 , it is a schematic diagram of component positions of the automatic control system for cooling the livestock and poultry house in summer with the wet curtain of the present invention.

An automatic control system for cooling the livestock and poultry house in summer with a wet curtain, wherein a plurality of wet curtain papers 1 are arranged on one side of the wall of the livestock and poultry house along the transverse direction and a part of the wall connected to it along the longitudinal direction , as the air inlet of the closed livestock and poultry house. The wet curtain paper 1 is connected with the wet curtain water supply system, and the wet curtain water supply system includes a water pump 2, a circulating pool 3 and an upper water pipe (not marked in the figure); A plurality of negative pressure fans 4 are provided as air outlets of the airtight livestock and poultry house; multiple rows of cages for raising animals are arranged vertically in the livestock and poultry house, and cages are arranged between adjacent two rows of cages for the management and maintenance of the breeder. working channel. In each row of cages, multiple groups of cages are set, the first group of cages near the air inlet is called the first frame 5, and the last group of cages is called the tail frame 6; in the livestock and poultry house, the wet curtain 1 A deflector 7 is set between the first frame 5, and the opening angle of the deflector 7 can be adjusted. By adjusting the opening angle of the deflector 7, the wind speed entering the livestock and poultry house can be adjusted; the controller 8 is arranged on In the workshop outside the livestock and poultry house.

The first temperature and humidity sensor 9 is set outside the livestock and poultry house, and a plurality of second temperature and humidity sensors 10 are set at a plurality of first frame 5 positions, and a plurality of third temperature and humidity sensors 11 are set at a plurality of tailstock 6 positions; A temperature and humidity sensor 9 , a second temperature and humidity sensor 10 and a third temperature and humidity sensor 11 are connected to the controller 8 respectively. Optionally, an air pressure sensor 12 may also be provided, and the air pressure sensor 12 is connected to the controller 8 .

Wherein, the first temperature and humidity sensor 9 will collect the temperature T _d (dry bulb temperature) and the relative humidity outside the poultry house in real time The air pressure sensor 12 will collect the air pressure P outside the livestock and poultry house in real time, and the second temperature and humidity sensor 10 will collect the temperature T1 and the relative humidity of the _first frame 5 in the livestock and poultry house in real time The third temperature and humidity sensor 11 will collect the temperature T and relative humidity at the _tailstock 6 places in the livestock and poultry house in real time The resulting data is sent to the controller 8 .

The control method of the automatic control system of a kind of livestock and poultry house summer wet curtain cooling of the present invention, it comprises the following steps:

1) According to the species and age of the animals kept in the house, select the appropriate temperature T _a for the house-raised environment.

Livestock and poultry raised on a large scale are endothermic animals. Within a certain range of ambient temperature, livestock and poultry can maintain a constant body temperature. This temperature range is called a constant body temperature zone. Once the ambient temperature is higher than this temperature, the animal's body temperature will start to rise, manifested as decreased appetite, increased respiratory rate, decreased digestive function, etc., which can lead to weakened physique, decreased productivity, and even heat death. For example, when the temperature exceeds 23°C, the egg production of chickens begins to decline, the eggs become smaller, and the eggshells become thinner. The weight gain of chicks slowed down at 27°C, and basically stopped at 38°C. When the temperature rises to 20°C, the milk production of dairy cows decreases, and when it rises to 30°C, the milk production of dairy cows drops sharply; when it exceeds 35°C, the milk production of dairy cows drops sharply. When the temperature exceeds 20°C, the daily gain of pigs of various body weights all decreases significantly, and when the temperature exceeds 30°C, it drops to a very low level.

Animals of the same species have different temperature requirements at different growth stages. Newborn animals have not yet fully formed their heat regulation function, and their body temperature varies greatly with the ambient temperature. Compared with adult animals, they require a higher ambient temperature.

At present, the more suitable ambient temperature for different growth stages of various animals is relatively clear. In this system, only the manager needs to input the corresponding environmental temperature of animals in each growth stage into the corresponding position in the control program according to the actual management requirements. The growth stage of the animal automatically adjusts T _a .

2) Determine the control mode of the wet curtain fan cooling system according to the determined temperature T _a

①Collect outdoor temperature T _d and relative humidity and atmospheric pressure P.

The first temperature sensor 9 and the air pressure sensor 12 are installed outdoors. The air temperature T _d and relative humidity outside the poultry house are collected in real time by the first temperature and humidity sensor 9 The air pressure P is collected in real time by the air pressure sensor 12, and the data is transmitted to the controller 8, and the system calculates the real-time wet bulb temperature value.

② From the outdoor temperature T _d , relative humidity And the atmospheric pressure P to calculate the wet bulb temperature T _w .

There is currently no method to directly calculate wet bulb temperature from temperature and relative humidity. This application uses the direct iterative method to calculate the wet bulb temperature T _w outside the livestock and poultry house when the temperature is 5-45°C and the relative humidity is 5%-100% under standard atmospheric pressure, and obtains the temperature Tw at The empirical calculation formula of wet bulb temperature under standard atmospheric pressure is shown in formula (1):

Among them, the unit of _Tw is ℃; _Td is the air temperature outside the house, the unit is ℃; is the relative humidity outside the livestock and poultry house, expressed with a decimal point in the formula, for example, when the relative humidity is 50%, Under the standard atmospheric pressure, the error range of the wet bulb temperature T _w outside the poultry house calculated by the calculation formula of the wet bulb temperature T _w is -0.515 ~ 0.289 ° C, which can meet the practical application production.

In areas with higher altitudes, the atmospheric pressure has a greater influence on the wet bulb temperature, so it is necessary to calibrate the wet bulb temperature T _w under the standard atmospheric pressure to obtain the wet bulb temperature under the actual atmospheric pressure

${\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

in, The unit of is ℃; ΔT _w is the correction value of thermodynamic wet bulb temperature, the unit is ℃; ΔP is the difference between the standard atmospheric pressure and the actual atmospheric pressure, the standard atmospheric pressure is 101325Pa, ΔP=101325-actual atmospheric pressure, the actual atmospheric pressure is collected by the air pressure sensor 12 and transmitted to the controller 8 in real time, and the unit is Pa.

③ Determine the air temperature t at the air inlet of the livestock and poultry house after passing through the cooling system of the wet curtain fan.

In the most ideal situation, the air outside the house can reduce the air temperature to the wet bulb temperature of the air after passing through the cooling system of the cooling curtain fan, that is to say, the cooling limit of the cooling curtain fan is the wet bulb temperature of the air. Therefore, after passing through the cooling curtain fan The closer the final air temperature is to the wet bulb temperature, the more fully the cooling process is carried out. The cooling efficiency η is usually used as an index to evaluate the cooling performance of evaporative cooling technology and equipment.

$\mathrm{<span\; class="notranslate">\; \&eta;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; t</span>}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}^{<span\; class="notranslate">\; *</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

Among them, 0<η<1, t is the air temperature at the air inlet of the livestock and poultry house after the air passes through the cooling pad, and the unit is °C.

Furthermore, the air temperature when entering the livestock and poultry house after being cooled by the wet curtain, that is, the air inlet temperature t is:

$\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&eta;</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&eta;</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

④ Determine the switching temperature of the "on-off" control mode and the intermittent control mode.

When t>T _a +Δt, the system enters the "on-off" wet curtain control mode. When t≤T _a +Δt, the system enters the intermittent wet curtain control mode.

The test proves that in the hot and dry areas of our country, when the wind speed across the curtain in the cooling system of the wet curtain fan is 1.0-1.5m/s, the cooling efficiency of the cooling system of the wet curtain fan is about 0.8, which can be obtained by inserting it into the formula (5) :

$\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.2</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.8</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

When the cooling efficiency of the cooling pad reaches n (wherein, n is 0.65~0.75), the actual temperature t ^* that can be achieved when the air enters the livestock and poultry house after being cooled by the cooling pad can be calculated according to the formula (5), expressed as for:

$\mathrm{<span\; class="notranslate">\; \&Delta;t</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; t</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.2</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; [</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

3) When the system is in the traditional "on-off" cooling pad control mode:

Once the water pump 2 is started, it will run continuously until it is switched to the intermittent wet curtain control mode.

When using the traditional "on-off" cooling pad control mode, once the water pump 2 is started, the cooling pad paper will be completely wetted, the temperature in the house will drop rapidly, and the system will achieve the best cooling effect. When this mode is adopted, apart from the influence of the wet curtain cooling system itself, the actual temperature in the house is determined by the dry bulb temperature and relative humidity outside the house, and is no longer subject to human control.

4) When the system is in the intermittent wet curtain control mode:

As shown in Figure 4, the intermittent wet curtain control mode is mainly controlled by adjusting the time when the water pump 2 is turned on and off, and the number of fans 4 turned on. When longitudinal ventilation is used in livestock and poultry houses, it is generally required that the temperature difference between the front and back of the house should not be greater than 2°C. In the "wet curtain-fan" longitudinal ventilation system, the temperature in the house generally increases gradually from the first rack 5 to the tail rack 6. Therefore, the lowest temperature in the house generally appears at the first rack 5, while the highest temperature in the house is Appears at tailstock 6. There are also differences in temperature at the same position among different columns. Generally, the wind speed in the aisle close to the wall is the lowest, and the temperature is higher than other aisles. Therefore, in order to achieve finer control, this embodiment suggests that it is not appropriate to arrange only one temperature and humidity sensor at the head frame 5 or the tail frame 6 .

In order to ensure that all the animals in the livestock and poultry house are in a more suitable temperature range, the maximum temperature in the house should not exceed T _a in this embodiment.

①The dry bulb temperature T1 and relative humidity at the _first shelf 5 are collected in real time by the second temperature and humidity sensor 10 When multiple second temperature and humidity sensors 10 are installed on the first rack 5, the minimum value is taken as the control parameter. The dry bulb temperature _T and the relative humidity at the tailstock 6 are collected in real time by the third temperature and humidity sensor 11 When multiple third temperature and humidity sensors 11 are installed on the tailstock 6, the maximum value is taken as the control parameter. ΔT is the difference between the temperature T at the _tailstock 6 and the temperature T1 at the _first shelf 5, that is, the temperature difference between the first shelf 5 and the tailstock 6:

ΔT = _end of T - T ₁ (8)

ΔT is a variable parameter. In practical applications, managers can input ΔT according to their own needs, and the system will carry out corresponding environmental regulation methods according to this input value. The system defaults to ΔT=2°C.

② When T ₁ ≤ T _a -ΔT, maintain the on-time of water pump 2; when T ₁ >T _a -ΔT, increase the on-time of water pump 2 and shorten the off-time of water pump 2. When the closing time of water pump 2 is shortened to 1 minute, if the opening and closing time of each cycle of water pump 2 is started, the system will automatically enter the "on-off" wet curtain control mode.

③ When T _end > T _a , increase the number of fans 4 to be turned on to increase the wind speed in the house and increase the ventilation volume, thereby reducing the temperature T _end at the tailstock 6. When T _end ≤ T _a , maintain the ventilation rate of fan 4.

At present, when livestock and poultry houses are vertically ventilated, multiple ordinary fans are often used as air outlets. The ventilation volume in the house is increased by increasing the number of fans turned on, and the ventilation volume increases in a stepwise manner with the increase of the number of fans turned on, as shown in Figure 2. In this application, the frequency conversion fan is effectively combined with different fans, so that the total ventilation volume in the house changes linearly with the increase of the number of fans turned on, as shown in Figure 3. The introduction of frequency conversion fan can effectively realize fine regulation of ventilation.

Claims (2)

1. A control method for an automatic control system of a wet curtain cooling in a livestock and poultry house in summer, wherein, in the automatic control system, the side wall of the livestock and poultry house along the transverse direction and a part of the wall along the longitudinal direction connected thereto A plurality of wet curtain papers (1) are arranged on it; a plurality of negative pressure fans (4) are arranged on the opposite wall; the wet curtain paper (1) is connected with the wet curtain water supply system, and the The wet curtain water supply system includes a water pump (2), a circulating pool (3) and a water supply pipe; Multiple rows of cages are set longitudinally in the livestock and poultry house, and passages are set between two adjacent rows of cages; in each row of cages, multiple sets of cages are set, among which the first set of cages near the end of the air inlet is the first rack ( 5), the last group of cages is the tail frame (6); the deflector (7) is set in the poultry house, between the wet curtain paper (1) and the first frame (5), and the controller (8) is arranged in a workshop outside a livestock building; First temperature and humidity sensors (9) are set outside the poultry house, multiple second temperature and humidity sensors (10) are set at the positions of multiple first racks (5), and multiple second temperature and humidity sensors (10) are set at the positions of multiple tailstocks (6). The third temperature and humidity sensor (11); The first temperature and humidity sensor (9), the second temperature and humidity sensor (10) and the third temperature and humidity sensor (11) are respectively connected to the controller (8); It is characterized by: The control method of the automatic control system includes the following steps: 1) According to the breed and the age of the animals raised in the house, select a suitable temperature T _a for raising in the house; 2) Determine the control mode of the wet curtain fan cooling system according to the determined temperature T _a ; When t>T _a +△t, the system enters the "on-off" wet curtain control mode; when t≤T _a +△t, the system enters the intermittent wet curtain control mode; Among them, t is the calculated temperature when the air enters the livestock and poultry house after being cooled by the wet curtain, and the unit is ° C; The temperature difference when entering the livestock and poultry house, the unit is ℃; 3) When the system is in the "on-off" wet curtain control mode: The started water pump (2) runs continuously until it is switched to the intermittent wet curtain control mode; 4) When the system is in intermittent wet curtain control mode: _1. The temperature T1 and the relative humidity at the first rack (5) are collected in real time by the second temperature and humidity sensor (10) When the first frame (5) was equipped with a plurality of second temperature and humidity sensors (10), the minimum value was used as the control parameter; the temperature _T and the relative humidity at the tailstock (6) were collected in real time by the third temperature and humidity sensors (11) When the tailstock (6) is equipped with a plurality of third temperature and humidity sensors (11), the maximum value is taken as the regulation parameter, and ΔT is the temperature T at the tailstock (6) and the temperature T _at the _first frame (5). The difference, that is, the temperature difference between the headstock (5) and the tailstock (6): △T = _end of T - T ₁ ; ② When T ₁ ≤ T _a -△T, maintain the on-time of the water pump (2); when T ₁ > T _a -△T, increase the on-time of the water pump (2) and shorten the off-time of the water pump (2); when the water pump ( 2) When the closing time is shortened to 1 minute, if the water pump (2) is started for each cycle opening and closing time, the system will automatically enter the "on-off" wet curtain control mode; ③When the _end of T>T _a , increase the number of fans (4) turned on; when the _end of T≤T _a , keep the number of fans (4) turned on unchanged. 2. the control method of the automatic control system of a kind of livestock and poultry house summer wet curtain cooling as claimed in claim 1, is characterized in that: In said step 2), $\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.2</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.8</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}^{<span\; class="notranslate">\; *</span>}$ $\mathrm{<span\; class="notranslate">\; \&Delta;</span>}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>$ Wherein, n is 0.65～0.75; T _d is the air temperature outside the house, which is collected in real time by the first temperature and humidity sensor (9), and the unit is °C; is the wet-bulb temperature outside the livestock and poultry house under the actual atmospheric pressure, in °C; in, In the formula, _Tw is the wet bulb temperature outside the livestock and poultry house under standard atmospheric pressure, in °C; Be relative humidity, be collected in real time by the first temperature and humidity sensor (9), represent with decimal point; ΔP is the difference of standard atmospheric pressure and actual atmospheric pressure; Real-time collection, the unit is Pa; in,