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How Do Heat Pumps Work?

Kundan Pandey Oct 24, 2018
Heat pumps, in the recent years, have gained prominence. Have you ever wondered how do they make a room or area hot or cold? It is indeed interesting to understand their working. Here we will tell you how heat pumps work.
Heat pumps are devices that are used to heat or cool homes, offices, or any other areas of your house. When they act as a heater, they draw necessary heat from the surrounding air or from the ground, and warm the rooms, whereas the reverse process is carried out in cooling the room.
Simply stated, when acting as a coolant, they draw out the heat or the warm air from the rooms, and thus make it cooler. Now, that is interesting! But how does it happen?
They are peculiar devices and are very efficient in their working. They are one of the best alternative energy source for home appliances and offices.They even give an excellent response in the areas where there is a mild climate.Installing them can help you save on your budget from the heavy expenses of the air conditioners and furnaces.
There are many types of heat pumps like air-source, ground-source, and geothermal heat pumps, but they all operate on the same basic principle of heat transfer i.e., instead of burning the fuel to create heat, the device transfers heat from one place to another. Let us look into the details and their working.

Basic Working Principle

A heat pump consists four main components: evaporator, compressor, condenser, and expansion device. The basic working is based on compression and expansion of a working fluid called 'refrigerant' that passes through all these components. The heat is extracted from the heat source in the evaporator that vaporizes the liquid.
The pressure of this gas is raised by the compressor that again warms up the gas and makes it pass through the condenser, where it gives out heat. This gas again condenses back to liquid, thereby repeating the cycle again. This whole process is carried out by electrical energy through which the compressor is powered.

Working of Air-source Heat Pumps

It is the most common type of heat pump. It transfers heat between the house and the outside air, and provides efficient heating and cooling in warm-climatic conditions.
If installed properly, it can deliver up to three times more heat energy than the electrical energy that is consumed by it.The refrigeration of this system consists of a compressor and two coils that are made of copper, which in turn are surrounded by aluminum fins to help in heat transfer.
When it is in heating mode, the heat from the air is extracted by the liquid refrigerant in the coils outside. This heat gets evaporated into gas.As it gets condensed back into liquid, the heat gets released from the refrigerant in indoor coils. The reversing valve that is present near the compressor is a versatile part of the pump.
It reverses the flow of the refrigerant because of which the system begins to operate in reverse direction. So, instead of pumping the heat inside the home, it releases the heat outside in the similar way an air conditioner does. The heat is absorbed from the inside and flows to the outside.

Working of Geothermal Heat Pumps

Geothermal energy is the energy that is buried deep beneath the Earth.
The word 'geothermal' is derived from the Greek words 'geo' (Earth) and 'thermos' (thermal/heat). It is a fact that the temperature beneath the surface of the earth lies between 50 ― 70℉.
This energy is usually more useful in the areas near plate tectonic boundaries as the magma near these locations often rises close to the surface. It is now a major subject of research and the scientists are trying to tap this form of energy to the fullest possible extent.
In the geothermal heat pumps, no fuel is required for the supply of the heat. Instead, the heat energy of the earth is supplied through pipes to the specific area where it is required. So, how is the heat supplied to long distances? Well, there are a series of pipes known as loops that are installed underground or beneath the surface of lakes.
With the help of these pipes, the heat is supplied to the homes. You must have observed the pipes submerged in rivers and lakes in many areas where the geothermal heat pumps are widely used. When the heat reaches its destination, electrically operated compressors and heat exchangers concentrate the heat energy.
This concentrated form of heat energy is at a higher temperature, and this is finally released inside the homes. Inside the house, the branched duct works to distribute the heat to various rooms.
In the summer season, the geothermal heat pumps draw the excess heat energy of the house and let the earth absorb it. Its working is exactly similar to that of the air conditioners that draw excess hot air from the house and blow cold air into the rooms!

Working of Ground-source Heat Pumps

The ground-source heat pumps are used in homes and work places. A typical ground source heat pump consists of a ground loop, a heat pump, and a heat distribution system. The ground loops consist of plastic pipes that are buried in the ground.
Generally, the pipes are either buried in boreholes or horizontal trenches. However, a vertical and slinky loop system is also used in many places. The pipe is filled with a mixture of water and antifreeze, which is circulated in the loop buried in your garden or any other suitable place.
When the liquid is traveling around the loop, it absorbs the heat energy of the ground. The length of the loop depends on the amount of heat required and the size of your home. The loop is coiled in trenches (two-meters deep) or laid flat, but if you have less space, then you can vertically install the loop to a depth of around 100 meters.
The efficiency of a ground-source heat pump is measured by a factor called the coefficient of performance that is a ratio of the amount of electricity used and the heat produced.
Heat pumps are cost-effective, efficient, and eco-friendly. However, ground source heat pumps require electricity that may be resource-consuming, but they are still being considered as a viable option for solving energy problems. One great advantage of heat pumps is that you don't need to install separate devices to heat and cool your home.