April 24, 2024
Evaporative Cooling

Harnessing Nature’s Cooling Power: Understanding Evaporative Cooling

How Evaporative Cooling Works

Evaporative cooling works on the basic principle of evaporation of a liquid into gas. In an evaporative cooler, air is pushed through a wet pad made of cellulose material. Water is continuously sprinkled on this pad to keep it moist. As hot air passes through the wet pad, some of the water evaporates into the air taking latent heat from the air. The air emerging out is cooler and more humid than the inlet air. The temperature drop depends on factors like dry bulb temperature of inlet air, wet bulb depression, and evaporation efficiency of the cooling pad. Typically, evaporative coolers can reduce air temperature by upto 17°C.

The process of evaporation is endothermic which means it absorbs heat from the surrounding. The heat required for phase change from liquid water to water vapour comes from the latent heat of vaporization. As the hot air passes through the wet cooling pads, it loses some of its sensible heat to evaporate the water. The process cools down the air without adding moisture but increases its humidity.

Evaporative Cooling System Components

A basic evaporative cooling system consists of following key components:

– Cooling Pads: Made of cellulose material, these pads are kept continuously moist by water sprinkling system. Hot air is blown through these pads for cooling.

– Water Distribution System: Evaporative Cooling It includes pipes, nozzles, and pumps to evenly distribute water on the cooling pads through sprinkling action.

– Blower/Fan: A robust blower or fan is used to push and pull hot air through the wet cooling pads. It pressurizes the air before letting it pass through pads for cooling.

– Water Reservoir: A water reservoir tank stores water supply for the distribution system. Water level sensors maintain optimum water level in the tank.

– Control Panel: An electronic control panel is used to automatically operate the blower, water pumps, and sensors as per set parameters.

– Ducting: Insulated rectangular ducts are used to route inlet hot air as well as outlet cooled air to desired areas for space conditioning.

Applications of Evaporative Cooling

Evaporative cooling technology has found widespread applications in buildings as well as industrial processes owing to its unique advantages:

– Residential and Commercial Buildings: Evaporative Cooling are extensively used in homes, offices, shops in hot arid regions where dry climate allows for significant drop in air temperature through evaporation.

– Greenhouses: For stable temperature and humidity control inside greenhouses where plants are cultivated, evaporative coolers prove to be an economical solution.

– Warehouses: They help maintain optimum temperature for storage of various goods and finished products in warehouses located in hot areas. Temperature fluctuations can otherwise damage products.

– Textile Industries: Evaporative coolers provide conditioned air for textile processes like spinning, weaving, bleaching etc. where consistent environmental parameters are required.

– Food and Beverage Industries: Industries involved in production, packaging and storing of food items, beverages utilize evaporative cooling units to control temperature, humidity and air quality inside manufacturing facilities.

– Power Plants: Cooling towers based on evaporative principle reject waste heat from steam in thermal power plants and lower the temperature of circulating water before it enters the condenser. This increases plant efficiency.

Advantages of Evaporative Cooling

There are some unique benefits of evaporative cooling technology that make it suitable for different applications:

– Low installation and running cost – Evaporative coolers have cheaper initial investment compared to other air conditioning systems. Their operational cost is 40-70% lesser than vapor compression units.

– Environment friendly – Being a passive cooling technique, Evaporative Cooling consume minimal electric power and cause negligible carbon footprint unlike vapor compression AC.

– Simple and robust design – Evaporative coolers have a basic design without many mechanical parts. They require low maintenance and have longer lifespan of over 10 years on average.

– Effectiveness in arid climates – Evaporative coolers can reduce temperatures by large margins in hot dry desert climates where wet bulb depression is high throughout the year enabling efficient cooling.

– Additional humidification – Cooled outlet air from evaporative systems has higher humidity levels which provides thermal comfort. This extra moisture is also useful many industrial processes.

– Zoning flexibility – Different zones in a building can be independently cooled as per load and comfort requirements by installing multiple evaporative coolers and associated ductworks.

– Power backup option – Fans of these units can run on renewable energy backups like solar PV, biomass gasifiers during power outages ensuring continuous cooling.

– Portability – Lightweight compact units with castors or fork pockets allow easy movement and installation of evaporative coolers at different locations as per changing needs.

1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it