Solar cooling is a method that turns sunlight into cooling energy for air conditioning and refrigeration. It gathers solar power and uses it to create cooling through a thermal process. This cooling process lowers and regulates temperatures for various purposes, like cooling air in buildings or making chilled water.
The basic principle of solar-driven refrigeration is similar to regular refrigeration. It involves evaporating a liquid refrigerant that absorbs heat and cools the surroundings.
The key difference between solar and conventional cooling is that solar cooling uses solar energy, not electricity. This idea works well because the sun’s energy is abundant during summers when air conditioning is needed the most.
Before discussing different cooling techniques, it’s essential to understand the distinction between solar air conditioning and cooling. Solar cooling cools a room or building by removing heat. On the other hand, solar air-conditioning ensures a room’s temperature and humidity are adjusted to make people feel comfortable inside.
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Solar Cooling Technologies
Four basic types of this cooling technologies are as follows-
1. Evaporative Cooling
The cooling effect of this technology relies on the natural process of evaporation. The liquid is evaporated to achieve coldness.
The process of evaporation results in the absorption of thermal energy. This causes a significant decrease in temperature for both the evaporated substance and its surrounding materials. Evaporative cooling devices are primarily utilized for air conditioning purposes.
2. Solar Ejector Cooling
The fluctuating pressure inside the machinery causes the liquid to undergo vaporization and evaporation, resulting in the cooling of both the component and its surrounding area. Ejectors are the foundation of this technology and are mostly used for both refrigeration and air conditioning.
3. Vapor Compression
In this refrigeration system, a circulating liquid refrigerant is employed, serving a crucial role in the cooling process. The liquid refrigerant acts as a medium that absorbs and draws heat away from the target area to be cooled, subsequently releasing and dissipating that heat elsewhere.
4. Sorption-Based Cooling
While vapor compression is a widely used technology, it suffers from issues related to vibration and noise. As an alternative, sorption-based cooling devices offer a different approach. These devices rely on sorbents to absorb and release liquids, creating a cooling effect. Sorption cooling systems encompass two distinct technologies:
- Absorption cooling: In this type of cooling, the liquid is dissolved in the sorbent during one stage of the process and then released in another stage.
- Adsorption cooling: Here, the liquid is bound to the surface of the sorbent during one stage of the process and subsequently released in another. Interestingly, during winter, the adsorption device can function as a heat pump.
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