Analysis of Six Cooling Methods for Greenhouse Greenhouses

As the weather warms up, we transition into summer—a season with longer daylight hours and ample rainfall, ideal for plant growth. However, excessive sunlight and high temperatures can hinder plant development, making cooling a crucial aspect of greenhouse production during the summer. When it comes to cooling greenhouses, while conditions vary by location, there are six primary methods: shading and cooling, wet-bulb evaporative cooling, micro-fog cooling, natural ventilation, roof sprinkler cooling, and air conditioning systems.

Certainly, here is the translated news content: In terms of dehumidification and cooling effects, air conditioning and similar equipment are commonly used, though this method is costlier and not suitable for widespread adoption among small-scale farmers. Using a wet-baffle fan for cooling takes advantage of the water evaporation cooling principle, paired with ventilation equipment to achieve the cooling goal. Although this is less expensive than air conditioning, it still requires appropriate equipment. Micro-fog cooling involves spraying water in the form of micrometer or 10-micrometer droplets into greenhouses, allowing for rapid evaporation. Utilizing the high latent heat of evaporation of water, it absorbs a large amount of heat from the air, and then expels the humid air outdoors to cool down the environment. However, this method undoubtedly increases the humidity inside the greenhouse, especially during the "sweat days" in the north when air humidity is already high, making it unsuitable for use. Many farmers use the roof sprinkling method for cooling, but it should be based on their own water source conditions.

Currently, shading and temperature reduction are still the most commonly used methods in actual production. Shading can block excessive sunlight from entering the outdoor environment, protecting crops from the harmful effects of intense light and creating ideal growing conditions. There are various methods of shading, including covering with shading nets, pouring mud or ink on greenhouse films to cool them down. The effectiveness of these different shading methods varies, with shading nets being the most prevalent. Their primary function is to block intense light and reduce greenhouse temperatures, with black and silver gray being the two most common colors on the market. Black shading nets have a high light-blocking rate and rapid cooling, making them suitable for short-term use in fields requiring meticulous management during the hot summer. Silver gray shading nets have a lower light-blocking rate and are better suited for light-loving vegetables and long-term coverage. Besides color, it's important to distinguish the material of the shading nets. The market offers two main types: high-density polyethylene and those made from recycled shading nets or plastic products. Shading nets produced with recycled materials have a lower luster, a harder texture, a strong odor, and a shorter lifespan, usually lasting only one year. In contrast, high-density polyethylene shading nets are more durable and resistant to aging, with a lifespan that can extend for several years.

As temperatures rise, it's no longer a matter of neglect to consider how to cool greenhouses. Farmers across the board can select cooling methods based on their specific circumstances. We suggest a primary focus on shading for cooling, complemented by other cooling methods tailored to the characteristics of the crops and climatic conditions. We believe that such a comprehensive approach will ensure the crops safely navigate through the scorching summer.