Evaporative Cooling

The Concept
Why an evaporative cooler works in an Irish climate
Comparison with Conventional Air Conditioning

Pharmacool Solutions

Case Studies (2.90MB - PDF document)

The Concept

Evaporative cooling is a process in which hot dry air is cooled by evaporating water into it. Air naturally soaks up water. This water requires a great deal of energy to change from a liquid to a gas. This energy has to come from the air during this evaporation. The effect of this is that on a typical hot day in the UK, air at 30°C and 35%RH will be cooled down to 20 °C.

This natural process is exploited by all mammals – sweat evaporates from the surface of the skin and the skin is cooled. For thousands of years it has been used to cool buildings and tents by hanging a wet cloth over an open door or window. As the air passes through the weave of the cloth the air is cooled and the atmosphere is made more comfortable.

A modern evaporative cooler consists of a fan which draws hot air across wet filter pads and discharges the cool air to its point of use.

As warm air passes over wet filter pads water naturally evaporates into the air. The air is cooled as it gives up the heat required to evaporate the water.

A more detailed explanation of the above is given in Section 9

Why does an evaporative cooler work in a UK Climate?

The pattern of the relationship between temperature and relative humidity on a typical hot day in Northern Europe is shown below.

It can be seen that the highest temperature coincides with the lowest humidity. This gives the greatest cooling when it is needed the most.

This also has a smoothing effect on the temperature of the air coming off the cooler which leads to more stable conditions.

Comparison with Conventional Air Conditioning

Evaporative Air Cooling	Refrigerated Air Conditioning
Uses only 10% of the electricity compared with conventional air conditioning	Uses large amounts of electrical power because of compressor.
As temperature rises efficiency improves	As temperature rises efficiency reduces
Cooling capacity is only limited by the air conditions. Up to 50KW of cooling can be achieved with only 1 KW of electricity used	Cooling is limited by theoretical Coefficient of Performance which means a maximum of 3.5 KW of cooling for 1 KW of electricity consumed
Open doors and windows do not affect performance	Open doors and windows significantly reduce performance.
Uses no harmful gases for its function.	Uses environmentally harmful gases.
Avoiding relative humidity below 50% significantly reduces static electricity problems	Leads to low relative humidity which can create high static electricity conditions
Few moving parts – one fan, one pump and three solenoid valves	Many moving parts including complex and expensive components such as the compressor
Easy and simple to service.	More difficult and expensive to service.
Always supplies 100% fresh air.	Only supplies about 15% fresh air. 85% is re-circulated. It is not fresh.
Air only cooled once.	Air cooled many times.
Has no upper limit on temperature	High ambient temperatures can lead equipment to shut down due to compressor overload
Lower purchase cost.	Higher cost to purchase.
Have bigger fans - pump large amounts of air.	Smaller fans - pump less air.
Temperature reduction limited by ambient Relative Humidity.	At higher Relative Humidities cooling is reduced due to greater latent heat load compared to sensible load.
Provides flow of fresh cool air.	Provides cool, recirculated, stale air.
Provides stable relative humidity levels which are more comfortable to work in	Can lead to low Relative Humidity which is not comfortable.
Simple to create positive pressure in buildings giving hygiene and control benefits	More difficult to create positive pressure with recirculation systems

Pharmacool Solutions

Pharmacool is a unique range of products designed specifically to meet the needs of the pharmaceutical distribution industry.

Based on a very clear understanding of the Irish Medicines Board recommendations for the storage of drugs at controlled room temperature, Pharmacool is the only solution on the market that comes with a full compliance guarantee, giving you complete piece of mind.

Each Pharmacool system is designed to suit the nature of your individual building, but all offer the same guarantee, and all offer low cost installation and low operating costs.

Pharmacool Bronze

Ideally suited to smaller distribution warehouses, or on site pharmacy stores, our Pharmacool Bronze system features fully automatic control, free cooling, and hassle free low maintenance operation, without the sophistication required for larger premises.

Pharmacool Silver

Great in medium sized warehouses, or larger premises that already have a monitoring and mapping system in place, Pharmacool Silver adds centralized electronic controls, with fail safe manual overrides, to the more basic Pharmacool Bronze.

Pharmacool Gold

Combining centralised electronic controls with sophisticated wireless temperature monitoring and reporting software; the Pharmacool Gold solution is ideal for large warehouses. In large spaces, considerable time can be saved through automatic monitoring of the MKT and absolute temperatures in order to demonstrate compliance, and integrating the temperature monitoring and control systems with each other avoids duplicated hardware, allows the cooling system to respond to the actual parameters required for compliance, and reduces maintenance costs.

Complete Environmental Control

Both Pharmacool Silver and the Pharmacool Gold can be extended to provide complete automatic control of all your environmental systems, whether existing or new. This can include cooling, ventilation, heating, economiser fans, door curtains and cold room systems, and offers fully integrated centralised control and (with Pharmacool Gold) monitoring, with more consistent temperatures throughout the year and reduced energy bills.