What is a greenhouse ventilation system and how does it work ?!

What is a greenhouse ventilation system ?!

The purpose of establishing a greenhouse and keeping plants inside it is to control all environmental parameters in all 12 months of the year. It is in this state that the greenhouse can reach its highest efficiency for the health and production of plants. In other words, the advantage of growing plants in the greenhouse is that people can control all the parameters. Therefore, if various parameters are not controlled by control tools and devices such as greenhouse ventilation system to control the temperature, it will fail in its goal.

So control all these parameters such as:

• • Temperature
  • Humidity
  • How to distribute air
  • air conditioner
  • Gases such as carbon dioxide and odors
  • Air flow

And other items are on the agenda of the greenhouse air conditioning system.
The ventilation system for its proper operation must take into account the items that are specific to each greenhouse. These include the weight of the greenhouse air, the altitude of the greenhouse and the amount of sunlight. Thus, for example, in areas at higher altitudes, the ventilation system must move a larger volume of air out of the greenhouse to do the work equivalent to greenhouses at lower altitudes.

What are the types of greenhouse ventilation systems?

What is a natural or passive ventilation system?

One of the greenhouse ventilation systems is mechanical and natural. In this way, depending on the location of the greenhouse, windows are installed on the sides and on the roof to transfer air. One of the main reasons for getting help from this type of greenhouse ventilation system is to reduce costs. In this case, the dimensions of the windows depend on the size of the greenhouse. In addition to the size of the greenhouse, which is a general parameter, there are other environmental parameters such as windy location of the greenhouse, the amount of pleasant light in it, season, tropical or cold region and humidity, which are specific to the geographical coordinates of each greenhouse. . This type of ventilation is also known as passive ventilation. Of course, this system is not completely natural, and in some cases, fans are placed in the way of these windows to speed up the work and make it easier.

The two main factors in this ventilation system are the effect of wind and temperature buoyancy. The effect of wind is the amount of wind blowing outside the greenhouse building, and temperature buoyancy also refers to the circulation of hot and cold air to create balance. In fact, wind plays a major role in passive or natural ventilation of the greenhouse, and its wind speed plays a major role in circulation. As mentioned earlier, the first benefit of using this type of ventilation system is cost reduction.

Such a system creates an open greenhouse. This means that the greenhouse interacts with the outside air. Of course, such interaction is not just about opening the side windows and ceiling, it means that the greenhouse is not a completely isolated environment in this case.

What is an active, active or fan greenhouse ventilation system?

It was said that greenhouses are considered open if they interact with the outside air. On the other hand, there are greenhouses known as closed greenhouses, which means that the environment inside them is completely closed, isolated and self-sufficient, and the control over the conditions of this greenhouse is higher and much more precise than the open greenhouse. In this case, the greenhouse is considered as a closed room, so it can use all air conditioning systems for its ventilation. Using active ventilation is the most efficient way to ventilate the greenhouse and help reduce the temperature. But its maintenance cost and performance are higher. When natural ventilation is not the answer for a greenhouse, it is essential to get help from this system.

Common systems such as:

• • Fan coil
  • Chiller and mini chiller
  • air conditioner
  • Heater unit
  • Econopack
  • boiler
  • Airwasher

And… are considered as types of this type of ventilation. Therefore, depending on the location and environmental conditions of a closed greenhouse, such as humidity or dryness, a variety of air conditioning systems are used.
In the meantime, it should be said that the heater unit is a device consisting of coils that are placed in a spiral inside a metal box. Finally, what can be seen from the heater unit is a metal box with fans that are responsible for circulating air on the coils.

Economop is also a heating and cooling device that uses gas combustion process for heating and for evaporation it either uses evaporation process such as water cooler or air circulation process between cold water pipes such as fan coil.

Fans

Fans are also one of the simplest and most common greenhouse ventilation tools. In fact, fans are a key way to actively ventilate the greenhouse and create airflow without regard to temperature conditions. Fans are used for uniform rotation of air in the greenhouse. Humidity and temperature in the air moving by the fan; They remain stable and provide an optimal environment for plant growth. However, fans have high costs over time and produce noise pollution that can be problematic in some areas.

Fans are a key method for active greenhouse ventilation, but are also sometimes used as an adjunct to natural or passive ventilation.

Greenhouse cooling methods

Cooling a greenhouse is not an easy task and is more expensive than heating the environment. When controlling the greenhouse temperature, directing the air flow in and out of the structure has the greatest effect on the greenhouse cooling. There are 4 main ways to cool a greenhouse:

1. Air conditioning systems
2. Evaporation system
3. Control the amount of light entering the greenhouse
4. Water spray on the roof

Evaporation system

The evaporation system, which seems to need further explanation, is such that it can convert even the hottest temperature to the right temperature for the greenhouse.

Evaporation system or wet walls are a common method of evaporative cooling system. Exterior vents and vents allow outside air to enter the greenhouse through such a wall. This warm air that enters from the outside environment, as it passes through the wet wall, removes moisture from it and thus reduces the air temperature and increases its humidity. This method can reduce the temperature by up to one degree Celsius.

The holes in the wall can be adjusted automatically or non-automatically by a control. This means that people inside the greenhouse can activate the operation of this greenhouse cooling system whenever they see fit. The advantages of this greenhouse system are as follows:

• It is most effective in areas with hot and dry weather
• Its energy consumption is low (but it has high water consumption)
• It only needs an opening to produce airflow in the greenhouse