Cool down in the middle of summer

The heat wave in midsummer has made orchids enter the difficult season, and it is also a time when the hearts of orchids are on fire. How to cool down is a topic often discussed by orchids. I learn from other people's experience and pass some experiments by consulting relevant materials. I have some experience to discuss with orchid friends, please put forward more valuable suggestions.

First, water mist cooling

Water fog can absorb a lot of heat in the air, and relevant data show that for every kilogram of water excited into a floating artificial fog, the effect is equal to dissolving seven kilograms of ice. Water changes from liquid to gaseous state, which increases the air humidity and reduces the air temperature. The whole process is an isoenthalpy process.

The only thing that can produce water fog is compression spray and ultrasonic atomizer.

Compression spray is to use pressure to spray water through the nozzle to produce atomization effect, or to use centrifugal pump to produce strong air pressure to splash water out of 0.01mm-0.03mm tiny water droplets to produce atomization effect. This kind of atomizer produces a relatively large fog cooling effect, which is also more suitable for large-scale orchid shed. However, due to the relatively large power of his compressor, the fog beads produced are relatively large, and the cooling persistence is not very good, so he often needs to open opportunities to bring unnecessary humidity to the orchid house.

Ultrasonic atomizer uses the principle of high-frequency vibration to make water produce small water droplets of 0.5 micron and atomize. The atomizer water particles are small and easy to penetrate into the air to have a better cooling effect, and often turn on the machine will not bring high humidity to the orchid room. Due to the small amount of atomization, it can only be used in a small area.

At present, the effect of the micro-fog system which is often used in modern greenhouse is very good, it has not only a large amount of atomization, but also small fog beads to cool and humidify.

Second, wet curtain cooling

The wet curtain cooling system is composed of special paper porous wet curtain, water circulation system and low pressure large flow energy saving fan. The wet curtain and the fan are respectively installed on two gables of the airtight house. When the fan is ventilated, it causes indoor negative pressure, forcing the outdoor unsaturated air to flow through the wet curtain porous wet surface, causing water evaporation to absorb a large amount of latent heat, thus reducing the temperature of the air itself. When the cooling system of wet curtain fan is running, the low temperature air after evaporation will be continuously introduced into the room for cooling, thus forcing the humidity of the dry bulb entering the indoor air to be reduced by 812 ℃ and constantly introduced into the room to prevent heat and cool down. And maintain the humidity of the air.

Third, spray the roof to cool down

Roof spray cooling is to spray water evenly on the roof of the glass greenhouse to reduce the temperature of the greenhouse. The principle is that when water flows into the glass roof, the heat in the greenhouse is taken away by the heat exchange between the water and the glass roof of the glass roof of the greenhouse, because the thermal conductivity of water is much greater than that of air. Therefore, the heat transfer intensity between water and glass is much greater than that between air and glass. In addition, when the thickness of the water film is more than 0.2 mm, all the energy of solar radiation is absorbed by the water film and carried next time, which is equivalent to sunshade.

The cooling effect of roof fountain needs a lower temperature water source, and its cooling effect is related to the water temperature and the flow of water on the roof. in principle, if the water is evenly distributed on the roof, the cooling effect can reach 6 ℃ to 8 ℃, but the current practice can not achieve this ideal situation, generally only 1 ℃ to 2 ℃. The disadvantage of roof fountain cooling is large water consumption, water scaling on the roof, affecting the light transmittance of glass, and complex cleaning.

4. Other ways to cool down

Air conditioning cooling this cooling method can achieve a minimum temperature of 18 ℃ and the cooling effect is long-lasting, but poor ventilation and poor humidity is a major weakness of air conditioning cooling.

The cooling effect of natural ventilation and forced ventilation is not ideal, because the air is also hot in hot weather, and the gas blown to bluegrass is also hot, but the air is relatively fresh.

Shading and cooling is to achieve the purpose of cooling by means of affecting the solar transmittance and preventing the sun from irradiating, which has obvious effect, but the cooling range is not large.

Evaporation cooling, through the evaporation of water to produce cooling effect, usually by setting up a sink or splashing water.