A two-stage evaporative cooling system can deliver cool indoor air with a relative humidity in the 50 %-65% range, while direct evaporative cooling systems typically condition the air at around 70% relative humidity.
According to the American Society of Heating and Engineers (ASHRAE), advanced two-stage evaporative coolers can use 60% -75% less electricity than conventional refrigerant-based AC systems.
In Two Stage Evaporative Cooling system, the first stage is Indirect Evaporative cooling. In Indirect Evaporative cooling stage(IEC) the water and hot air travel in different channels. Water and hot air do not come in direct contact with each other. This is why it is called Indirect Evaporative cooling. Dual-stage combined is also called the Indirect Direct Evaporative Cooling system. The heat exchanger used is a cross-flow, plate-type polymeric exchanger. Warm, primary air flows in enclosed channels. It gives up its heat to water films flowing down the other side of the polymeric plates. A secondary air stream flowing in the direction opposite to the water evaporates water before it is exhausted outside. Thus, the primary air is cooled without any moisture addition. In Two-stage Evaporative cooling, no free moisture is added to the incoming air and because of this fact it is sometimes called dry evaporative cooling. Two-stage Evaporative coolers are also known as Indirect Direct Evaporative Cooler. Aayushi Engineering has used this two-stage evaporative system in replacement of air conditioner for comfort cooling large industrial spaces where air conditioning is not feasible. All food processing applications, Industrial Kitchens where positive pressure is a concern and need a large volume of cool & fresh air, Indirect Direct Evaporative cooling system is the best cooling option.
A. How Does Two Stage Evaporative Cooling System Work?
2- stage evaporative cooling system also called Indirect Direct Evaporative cooling represents the most advanced cooling system – utilizing evaporative cooling technology. This cooling option is much more energy-efficient than cooling with refrigerant (standard air conditioning).It is most suitable for large open and semi-open spaces or where sufficient ventilation provisions are available.
The working principle of Two-stage evaporative cooling in terms of the stages of cooling is based on Evaporative cooling technology. In the first stage, hot outside air and water pass inside a heat exchanger in different channels. Moreover, during this initial cooling phase, the incoming air stream doesn’t pick up any extra moisture. In the second stage of the two-stage Evaporative Cooling system, the same air stream passes through a water-soaked pad where the additional cooling takes place and the air picks up some additional moisture.
A two-stage evaporative cooling system can deliver cool indoor air with Low relative humidity compared to direct evaporative cooling systems which typically deliver the air at around 70%-80% relative humidity.
According to the American Society of Heating and Engineers (ASHRAE), two-stage evaporative coolers use 60%-75% less electricity than conventional refrigerant-based AC systems. Therefore, evaporative cooling is a very attractive option in terms of energy efficiency. However, it is important to note that these systems are best suited for the hot, dry climate found in India.
B. Advantages Of The Two-Stage Or Indirect Direct Evaporative Cooling System
- This technology helps in reducing the running cost by consuming less electricity. Further Indirect Evaporative cooling is used where dry air or low humidity supply air is needed.
- It is an energy-efficient and cost-effective solution. Indirect Evaporative Cooler consumes almost half the energy required by an air conditioner. Moreover, Capital Expense is also relatively low.
- Two-stage evaporative cooling systems help in cooling the conditioning space with 100% fresh air. These are designed for 25-35 ACPH for better cooling and adequate ventilation.
- It is an eco-friendly cooling system as no harmful refrigerants are used.
- Aayushi Engineering uses Hi-efficiency sensible Heat Exchangers . The Centrifugal Blowers from Nicotra / Krugger.The Electric motor used is IP 55 Protected with IE2 /IE3 efficiency. The standard make Motors of Siemens / ABB /CG /Havells are used.