DESIGN CRITERIA OF GREENHOUSE FOR COOLING AND HEALTHY PURPOSE
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| Design criteria of greenhouse for cooling and healthy purpose |
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□ Sufficient sunlight, temperature and humidity are required to produce polyethylene greenhouse crops. Water, fuel and electricity make possible the environmental control which is essential for a favorable result.
□ Plants that require multiple daytime temperatures of 70 to 80 degrees Fahrenheit and a cool night temperature of 50 degrees Fahrenheit are, for example, azalea, smoothie, carnation, camellia, lettuce, reddish, aster, carrot, snapdragon, sweet pea , etc. .
□ and some require a warm greenhouse with a night temperature of around 65 degrees Fahrenheit. These include rose, tomato, lily, orchid, daffodil, and chrysanthemum.
GALZING
□ the transparent or translucent cover of a greenhouse. Example of glass, plastic film, rigid plastic panels.
GREENHOUSE COOLING
□ these are various active and passive ways of cooling the greenhouse which are briefly explained below: -
VENTILATION
□ The change in slope between the greenhouse effect in the comment and the external environment is known as ventilation. This exchange kept the internal temperature of the greenhouse closer to the external temperature.
□ there are two ventilation systems in the greenhouse: -
1 natural ventilation
2 mechanical ventilation
NATURAL VENTILATION
□ this process of replenishing and removing the ears through and into space without using a mechanical system. It refers to the soil in the outer ear of the greenhouse due to differences in pressure or temperature.
□ Advantage: -
1. improvement of the air quality in the greenhouse.
2. 2. Reduction of greenhouse gas emissions.
3. 3. Increase worker efficiency.
□ Disadvantage: -
1. ineffective on a hot day.
MECHANICAL VENTILATION
□ Circulate air using ducts and fans rather than relying on airflow through confined natural spaces in the greenhouse.
BENEFIT
1. Better indoor air quality.
2. 2. Provides adequate fresh airflow along with a suitable location for intake and exhaust.
3. 3. Allows a constant flow of filtered outdoor air.
ADDITIONAL COOLING OR GREENHOUSE COOLING
□ When regular ventilation is unable to provide sufficient cooling for greenhouse control, additional cooling is required.
Two cooling systems: -
1. Pad and fan
2. 2. Fog system
3. Both are commonly used in family homes.
PAD AND FAN
□ This can work in conjunction with mechanical ventilation. A functioning cooling panel is installed in the ventilation opening, which cools the incoming air. As the air moves through the greenhouse to the exhaust fan, it collects heat from the greenhouse's involvement. Therefore, the pad and the ventilation system undergo a temperature gradient between the entrance and exit of the greenhouse.
FOG SYSTEM
□ The spray nozzle can be installed throughout the greenhouse, resulting in a more uniform cooling pattern than the fan and pad system. The recommended spacing is one nozzle for every 5200 square feet of growing area.
□ Advantage: -
1. The water pressure is very high for any fine droplet production.
2. A small amount of water is required at a rate of between 1 and 1.2 gallons per hour.
3. Water treatment and a high pressure pump are required to operate a sprinkler system. However, it is very expensive compared to the pad and fan system.
CONTROL OF HUMIDITY
CONTROL OF HUMIDITY
□ A healthy plant can transfer a lot of water, resulting in an increase in the humidity of the greenhouse hair.
(Relative humidity greater than 80-85% should be avoided as it can increase the incidence of disease and reduce plant transpiration).
□ Efficient ventilation requires a pad and fan or nebulizer that increases the relative humidity of the cooling system.
VAPOR PRESSURE DEFICIENCY
□ It is a measure of the difference between the amount of moisture contained in the air at any given time and the amount of moisture it can hold at that temperature when the year would be saturated, which is the beginning of condensation, also known as the temperature of the Dew point. A high vapor pressure deficit value encourages transpiration, but too high a value can cause wilting. It decreases the value of the vapor pressure deficit in transpiration and leads to the formation of condensation on the surfaces of the leaves and the greenhouse. The typical measurement of greenhouse vapor pressure deficit ranges from 0 to 1 pound per square inch.
PASSIVE COOLING
SHADING
□ The shading content helps reduce the energy load in a greenhouse crop during hot and summer conditions and helps reduce heat radiation losses at night. Energy savings of up to 30% have been reported.
□ The mobile container can be operated automatically with a motorized system controlled by a light sensor or a timer.
□ When shading systems are located near a heat source (for example, an air heater or carbon dioxide burner), it is a good idea to install low-flammable material. It will stop the fire when all the curtains are closed.
□ For cooling shaded nursery areas with nets during the summer. During the winter, the shade net protects the plants from the cold or very low temperatures.
GREENHOUSE HEATING
□ It is an expensive activity, usually done with gas, hydroelectricity, solar or geothermal energy or heat.
□ is rare in Indian.
□ Requires a cool environment, needs electricity, greenhouse heating requirements depend on the amount of heat loss from the structures.
□ Heat loss from a greenhouse generally occurs for all three modes of heat transfer: -
1. Conduction: - Heat is conducted through substances or between objects by direct physical contact. It depends on the area, the length of the path, the temperature differences and the physical properties of the substances.
2. This heat transfer mode may be minimized by the insulation applicator.
2. Convection: - Heat transfer by gas or liquid. It occurs due to ventilation and infiltration (fans and air leaks).
3. RADIATION: - Heat transfer occurs between two bodies without direct contact or the necessity for a medium like air.
The rate of heat transfer by radiation varies with the area of an object, the temperature and the characteristics of the surface of the two bodies. Such heat loss from an object can be reduced by surrounding the object with a highly reflective opaque barrier.
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3 Comments
The importance of greenhouse heaters stems from the fact that temperatures fluctuate throughout the day and night. It may eventually fall to a level that is harmful to the plants.
ReplyDeleteVery good points you wrote here..Great stuff...I think you've made some truly interesting points.Keep up the good work. cooling-heating
ReplyDeleteThanks for your valuable comments.
ReplyDeleteIf you have any question let me know