Cooling method and precautions of mushroom greenhouse in summer

Although various regions situations are different green house cooling has six ways: sun-shade cooling, wet curtain and fan cooling, micro-fog cooling, natural ventilation cooling, spray cooling from roof and equipment cooling such as air-conditioner.

1. Sun-shade cooling

At present in practical production most adopted method is sun-shade cooling, which could block redundant sunlight and protect the crop from burning by strong light, and create suitable growth conditions for the crop. Sun-shade methods are various, some cover with sunshade net to cool, some splash mud or spill ink on shed film to cool. 

We need pay attention to that different sunshade methods have different sunshade effects, most commonly used is sunshade net. Its main function is obstructing strong light and cooling shed temperature, in the market there are two kinds of black and silver gray. Shading coefficient of Black sunshade net is high and could cool quickly, it is suitable to be used for short-term cover on field parcel which need fine management. Shading coefficient of silver gray net is low, it is suitable to be use for positive vegetables and long-term cover. They can be distinguished by color or by texture.

2. Wet curtain and fan cooling

The cooling method that utilizes temperature cooling theory of water evaporation and is matched with using related equipment to conduct ventilation is called wet curtain and fan. Wet curtain and fan use temperature cooling theory of water evaporation to realize the goal of cooling. Although wet curtain and fan have low cost than air-conditioner, it need equipped with corresponding equipment. When cooling open fan, the fan will extract compulsorily the air in greenhouse and form negative pressure; at the same time water pump will pour water on wet curtain. When outdoor air is inhaled in by negative pressure, it will pass through the gap of wet curtain, during pass the air will exchange with the steam on wet medium surface, the air sensible heat will be changed into latent heat of vaporization, then water is evaporated and realize cooling, cold air flows through greenhouse, after absorbing indoor heat the air is exhausted with the fan, therefore achieve cooling. 

3. Micro-fog cooling

Micro-fog cooling is to spray water with fog droplets state of micron-grade or 10 micron-grades into greenhouse, make it evaporate quickly, and utilize high latent heat of water evaporation, greatly absorb air heat, and then discharge moister air out of greenhouse and achieve cooling. Although it seems there are no unreasonable, this way will increase humidity in greenhouse, so when encountering “sauna weather” in north and air humidity is high itself, this way should not be adopted. 

4. Natural ventilation cooling

Generally ventilation has three aims: first is to discharge and decrease heat so as to cool; second is to exclude water; third is to adjust air ingredients in greenhouse, discharge harmful air and improve CO2 content. In summer indoor cooling is its main aim. Natural ventilation usually sets up windows on the roof or wall of greenhouse, ventilate with hot-pressing or wind pressure, and adjust window-open degree to regulate ventilation quantity.

5. Spray cooling from roof

Spray cooling from roof is adopted by many farmers, but it should be subject to water source condition. We need pay attention to that if spray system is designed reasonably directly affect water saving effect, in general spray system mainly includes: water source, pressing(controlling) equipment, pipelines and shower nozzle.

6. Equipment cooling such as air-conditioner

If you ask which way of greenhouse cooling is the simplest? I believe many friends will choose air-conditioner. Indeed from effect of dehumidification and cooling, using air-conditioner is the best. But this way the cost is high, at present using air conditioning system as greenhouse temperature control system is very few.

In hot summer the temperature of greenhouse sometimes will reach over 40℃, if not conducting cooling treatment it will cause disadvantageous influence on crops. Above methods are only for reference, some cooling methods need prepare in advance such as spray system and water net. In addition i would like to remind farmer friends that with temperature increase you should well manage greenhouse and prevent drought and pest and disease damage.