Applications which have simultaneous cooling & heating load requirement is the potential candidate for this kind of system. The recovery of condensation heat is efficient way of producing Hot water. This will reduce condenser heat load & thereby reduce heat dissipation cost of chiller system.
It also reduces the cost of additional heater/boiler otherwise needed for hot water generation.
Where we need this system? First We will see the applications where using heat recovery chiller will give you benefits. Check below applications.
- Heating Load Requirement for building:
Heat recovery device can be used to cover entire heat load of the building with total heat recovery option along with cooling load demand.
The auxiliary heating device is recommended to cover the thermal energy demand when the chiller is not in operation or is in part load operation
- Preheating of Water for Domestic or Industrial use:
In this arrangement recovery device only covers the part of the heat load by Heating the water before it enters the main heating device like boilers. It reduces the size & power requirement of main heating device.
- Heating of water for Swimming pools, Hotels & SPA:
These are always necessary heating requirement along with building cooling load in most of the application likes hotels. For which Hot water can be generated for free with use of Heat recovery exchangers.
- Domestic Hot Water requirement by use of heat recovery..
Typical Application may include Hotels, Hospitals, Dairy, Pharma & Processing industries etc..
Heat recovery can be done in two methods:
- Partial Heat Recovery: Recovers around 10 to 30% of total heat dispersed by cooling process. That would otherwise be disposed of to external source through condenser.
With this arrangement power input can be reduced by 3 to 5%.
- Total Heat Recovery: Recovers 100% of total heat rejected during cooling process. In this operation no heat will be rejected to external thermal source (by condenser or cooling tower). All the heat dispersed will be exchanged in recovery exchanger to heat the water to required temperature. (The dispersed heating capacity is equal to sum of cooling capacity & the electrical input capacity of the compressor)
In this condition overall efficiency of the unit is very high & can be expressed as (cooling output power + heating output from recovery) / (total power input)
Partial Heat recovery arrangement:
Total Heat recovery arrangement:
Above are typical arrangement used in Air-cooled chillers.
Some water cooled chillers arrangement uses a heat exchanger outside of the water-cooled condenser. Instead of rejecting heat to the cooling tower, heat is recovered from the condenser water.
In another method, this heat recovery can take place directly from hot refrigerant in the refrigeration circuit by using an additional condenser bundle, piped in parallel with the normal condenser. The heating circuit and cooling tower circuit are separate, preventing cross contamination.
Benefits of Heat Recovery Chillers:
- Reduce the need of additional heat generator /boiler etc or at least reduce power demand of heating device.
- Reduce water heater energy usage by up to 50 percent.
- Improve the performance & extend the life of refrigeration compressor and water heaters.
- Typical payback period is 2.5 to 5 years.
- Energy saving of around 180 to 200 TR per year in larger application.
- Saving of yearly 30 to 40 lakhs in conditions with high cooling & heating demand year round.
- COP of more than 6.0 can be achieved which can be 5 times higher as compared to separate system used for cooling & heating like (Chiller+Boiler).
- Total output will be greater (cooling+heating) with same energy input. So overall higher effeciency.