Heat Transfer Additives

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Chillers are one of the largest energy guzzlers in any industrial setup. A chiller system can, today, have a full load efficiency of 0.5 – 0.6 kW/TR for the entire chiller plant. The most efficient chiller systems have efficiencies of about 0.47 kW/TR. Getting a system’s efficiency to this level is possible with smart investments and operations.

One definite way to increase a chiller system’s efficiency to use a more efficient heat transfer fluid. The function of a heat transfer fluid, in an air conditioning system, is to absorb heat from the space that is to be cooled and to transfer it back to the refrigerant in the evaporator. Water has a thermal conductivity of around 0.6 W/m. K (click here) at standard temperature and is not the best retainer and conductor of heat (copper, in comparison, has a thermal conductivity of 385 W/m. K). But, most chillers use water because it has the best liquid conductivity among liquids, is cheap and easily available.

This additive, a newly available technology, when added to water in a chiller system, has been found to result in reducing the chiller’s energy consumption by as high as 35%. No matter what the energy source, or how efficient the chiller is, this technology improves the efficiency of the whole system by transferring heat more effectively.

TECHNOLOGY

During convective heat transfer, particles adhere to a solid hot surface for a short period due to a phenomenon called the non slip flow (click here). Fluid particles absorb heat and recirculate it, transferring the heat between different layers of fluids.

The additive contain stably suspended nano-particles that rearrange the molecular structure of the fluid. When added to water, they increase the number of particles present per unit volume (density) increasing the surface area which consequently increases the thermal conductivity of the fluid. As a result, the coolant liquid (additive + water mix) draws more heat from the surface. In short, the water + additive mixture has a higher heat transfer coefficient and thus becomes a better heat transfer medium.

The additive:

 

  • Has an operating range of -58 °F to +250°F ( -50 °C to 121 °C)
  • Is 100% Freeze Protected
  • Is less viscous and can be used in place of water/glycol

ENERGY EFFICIENCY

Say for instance, with only water as a cooling medium, and a required ambient temperature of 15 °C, the inlet temperature is 7 °C and the outlet temperature is 12 °C. The water has to be circulated a few times before the desired temperature of 15 °C is reached and the AHU cuts off. The difference between inlet and outlet, say Delta T, in this case is 5 °C.

Using the water + additive mixture as the coolant will help absorb heat more efficiently. In this case, on the evaporator side, with a supply temperature of 7 °C, the return temperature would be lower, at, say, around 10 °C because of better heat absorption. The circulation will have to be done fewer number of times to achieve required ambient temperature. Once the temperature is achieved, AHU will cut off and the fluid will be bypassed.

Due to a smaller Delta T, the compressor’s work is reduced. Also, due to the fewer number of circulations and a faster cut-off, the compressor works on lower lift. When compressor works on lower lift, it consumes comparatively lesser energy while generating the same amount of cooling effect (assuming all other parameters are constant). The difference in energy required by a system when running only on water or glycol and a system running on the water + additive mixture can be as high as 35%.

This technology is most suitable for closed-loop cooling systems where efficiency is achieved by reducing the run-time of associated equipment. Hence, there is also the added benefit of an increase in equipment life along with lower maintenance expenses. Other advantages are:

 

  • No equipment change required
  • Reduced carbon emissions

RISKS 

The water + additive mixture as the coolant, being a new technology, brings up several questions and risk factors. What if the chiller equipment gets damaged? Is the additive safe? The additive is secured by the 2nd largest insurance company in the world and any damage to your system caused by using it is insured. In fact, there have been no claims up till now and additional coverage can be provided.

The additive also comes with 8 years manufacturer’s warranty.

It has been tested by various well-known laboratories including Intertek and is:

 

  • Non-corrosive
  • Non-carcinogenic
  • Non-flammable or explosive
  • Biodegradable & Recyclable

INVESTMENT RETURNS

The additive has resulted in savings of 35% versus water or glycol. It:

 

  • Has a life expectancy of 15-20 years
  • Pays back within 2-3 years

It is currently being used with great success at Bajaj, Mahindra, Club Mahindra, VE Commercial Vehicles, Ultratech, Luminous Inverters, among others.

Energyhive can help you realise similar success for your chiller units. Contact us today to know more.

 

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