Laboratory Chillers

A Chiller is used in the laboratory or in any other industry is basically a water-cooled air conditioning system. A laboratory chiller cools the inside air, thus making the environment more comfortable as well as productive. A chiller is like an air conditioner in the way that both uses a compressor based cooling system. Unlike an AC the lab Chiller cools and controls the temperature of liquids in place of air. Temperature controller, Condenser, Recirculating pump and Reservoir are some of the integral components of a laboratory chiller. A Chiller provides stable temperature, flow and pressure after it is programmed by an user according to the needs. Harmful particles are kept at bay and out of the system by using an internal strainer. Some of the new range of Laboratory chillers offer the folowing features.

• Non-corrodible coolant circuits
• Environmental-friendly refrigerants
• Use of highly efficient coaxial evaporators
• A PID controller (Proportional–integral–derivative controller) enables maintaining an uniform temperature of +/-0.5 deg C.
• An easily visible liquid level indicator
• Removable venting grids for easy cleaning of the condenser
• LED temperature display

Lab Chiller Selection
The importance of the Chillers can be judged from the fact that Chillers typically consume around 25 to 50 percent of a laboratory's annual spending on energy. So selecting the right kind of Chiller is very important to get optimum results.

Select the appropriately sized recirculating chiller means lessening of the energy budget. The optimum size depens upon the quantum of heat being generated. Along with that extra power to maintain temperature under changing loads is also to be noted.

Generally the manufacturer of the device that is being cooled will furnish the necessary heat removal information. In case the information is unavailable, the following formula will help to calculate the heat load of the system:


Where :
= It is the difference that exists between incoming and outgoing tap water temperature denoted by T of the instrument. The temperature should be measured very carefully employing the same thermometer for both the locations. Degrees in Celsius or Fahrenheit both are ok.
S = This denotes the number of seconds needed to fill up a 1 liter container.
K = Conversion constant for water's density and specific heat.
When measured in Celsius: Watts =
When measured in Fahrenheit: Watts =

Other Considerations:

• When ambient temperature of the cooling location is more than 20°C, there is need to add just 1% to the calculated wattage for each half degree centigrade (0.5°C) above 20°C.
• When the operation is going at 50Hz, there is need to add 20% to the calculated wattage.
• If line voltage is seen to be always below the rated voltage, or the work is carried out at high altitude, then 10% is to be added to the calculated wattage.

Conversions:
BTU’s / hr = (watts) * 3.413 ( BTU stands for British Thermal Unit)
Tons = (BTU’s / hr) / 12,000

Types of Laboratory Chillers
Portable Chiller
Portable Chillers are very popular in laboratories of various sizes. They are basically liquid cooling systems on casters which provides easy relocation from one application to the other. A Portable Chiller can be applied for cooling more than one heat generating devices.

Air-cooled chiller
Air- cooled chillers can absorb heat from process water and then subsequently transfers the heat to the surrounding air. Air Cooled Chillers are typically employed in applications where there is no problem with additional heat discharged by them.However in comparison to water cooled units they consume approximately 10% more power. Other features include the following
» No requirement for a cooling tower and condense water pump
» Less maintenance as compared to water Cooled units

Water-cooled chiller
Water cooled Chillers typically absorb heat from process water and then subsequently shift it to a separate water source like cooling tower, lakes, pond etc. They suit large capacity applications, where the heat generated by air-cooled chillers can be a source of potential trouble. Water cooled chiller are also great when there is already a cooling tower in place, or when the requirement is to have an optimal power consumption efficiency. On the floip side Water- cooled chillers need condenser water treatment to remove the build up of e mineral. Mineral deposits result in poor heat transfer situations, reducing the overall efficiency of the unit.