Working of a Heat Pump

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Heat pumps are devices that deliver hot water or air. They are a sustainable heating solution that use mechanical energy to transfer heat between areas with a negative heat differential.

Industrial applications, that require hot water or low temperature heat (< 90 C) for their process applications, typically use electrical heaters or fossil-fuel based solutions. Not only does this leave a massive carbon footprint but it offers scope for more energy efficient heat generation like heat pumps, which is a reliable and very cost effective alternative.

PROCESS

A heat pump uses ambient heat and a small amount of primary energy to hit the required temperatures through the use of compressors, evaporators and condensers. Based on the source of ambient heat, they are classified into air, water or ground-source heat pumps.

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In an air to water heat pump, slightly superheated vapour from the outdoor heat exchanger is fed to the compressor. It then leaves the compressor as superheated vapour (fed with a small amount of electricity) at a high temperature and pressure and heads to the plate heat exchanger where water from the tank absorbs heat from the refrigerant. The water from the tank is circulated until the desired temperature is reached. It can be now used for applications up to 90° C. Air to air and Ground to Air Heat pumps work on similar principle.

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With applications across sectors like food processing, automobile, cold storage, pharmaceutical, dairy, etc. heat pumps are proving to be effective for low temperature heat requirements. They can be used for process heating, process cooling, and air conditioning.

ENERGY EFFICIENCY

A heat pump has multiple advantages over traditional heating mechanisms:

  • For about 1kw of input electricity, a heat pump is able to generate 3.5 kW to 4 kW of output energy by using ambient energy. Efficiency of a heat pump can thus reach as high as 350% depending on the temperature to be maintained.
  • They offer simultaneous delivery of heating and cooling
  • Maintenance and running costs are minimal
  • They have a small carbon footprint and zero emissions. In fact, if the primary electricity is renewable in nature, the carbon footprint can be zero.

INVESTMENT RETURN

To understand the cost versus benefit analysis of a heat pump, let us consider an industrial application of a heating mechanism.

Assuming:

Number of operational days/year are 330 (B)

Cost of one unit of power to be Rs. 8.50/kWh (C)

DevicePower Consumption/Day (A)

Total cost of running/year

(A)*(B)*(C)

Electric Heater300 kWRs. 8,41,500.00
Heat Pump (COP of 2.4)125 kWRs. 3,50,625.00

Net saving in cost per year

= Cost to run the heater for a year – Cost to run the heat pump for a year

= Rs. 8,41,500.00 – Rs. 3,50,625.00

= Rs. 4,90,875.00

If we consider the cost of the project which includes supply of the new heat pump, installation, testing, and commissioning to be an amount of Rs. 7,50,000, the payback period in months would be

= (Cost of project / Net saving per year) * 12 months

= (Rs. 7,50,000.00 / Rs. 4,90,875.00) * 12 months

≈ 18 months

Typical lifespan of a heat pump is around 15 years. Payback on a heat pump is less than two years. This means that users get same output for low operating cost for the next 13 years.

While the first year of heat pump installation, typically, comes under warranty. From the second year onwards, an Annual Maintenance is required for which an AMC is executed with a yearly cost (usually a percentage of capital cost) and escalation.

For a 15 year lifecycle, levelised cost per year (before tax) of the AMC can be calculated as

= (total cost of AMC from year 2 to 15) / 15 years

= Σ (x% of project cost * (1+ y)n )  where n ranges from 0 to 13

Where x is the AMC cost, y is the annual escalation rate

Heat pumps are currently being used by companies like Toyota Kirloskar, TVS group, Royal Enfield, Ashok Leyland, Saint Gobain, Daimler, Royal Orchid hotels, Aloft hotels, Godrej and Boyce, etc with outstanding results.

Energyhive can connect you with partners who can offer estimate on setting up heat pumps for industrial applications, install devices, and help understand savings potential. Energyhive also works with companies that have alternate business models if capital investment is an issue.

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