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Working Principle of Heat Pumps for Dummies

Heat pumps explained

Heat pipes can explained. we talk about heat pumps and how heat pumps work. At different types of heat pumps, their applications, and animated projects to develop your HVAC engineering knowledge. how heat pumps work, Heat pumps for dummies air-to-air heat pumps, air-to-water heat pumps, ground source heat pumps, and water source heat pumps.

A key feature of heat pumps is how energy efficient they are, and Danfoss has everything you need to ensure your heat pump runs “360° energy efficient”. They’ve also created a heat pump website with business cases, case stories, e-courses and a fun diagram like the one seen on this channel so you can see how it all comes together. the first thing we’re going to look at the air-to-air heat pump. These are the simplest types of heat pumps. They often look similar to a standard air conditioning split unit, with one unit located outside and the other unit located inside.

These can only function as a heating device, but a more popular option is a device that can provide both heating and cooling using a reversing valve. Heat pumps for dummies We have described how reversing

valves work in our previous video tutorial, click here to watch.
There are a few ways to configure a reversing heat pump, but I’ll show you a simple, common example.

The Main Component

We have a compressor, reversing valve, internal heat exchanger, expansion valve with non-return valve bypass, bi-directional filter drier, a sight glass, and another expansion valve with non-return valve bypass. Then we have the external heat exchanger. We have a controller and several temperature and pressure sensors around the system.

Main Component Heat Pumps for Dummies

In heating mode, the refrigerant leaves the compressor as high-pressure, high-temperature vapor and enters the reversing valve. The reversing valve can placed in the heating mode so that the refrigerant passes through the indoor unit. Cool air can be blown over the indoor unit heat exchanger, removing some of the heat energy and providing heat to the room. As heat is removed, the refrigerant condenses. After giving up some of its energy, the refrigerant exits as a high-pressure, slightly cooled, liquid. The refrigerant then comes to the expansion valve and the bypass, the expansion valve closes, so the liquid refrigerant passes through the non-return valve, filter drier, and sight glass, then through the expansion valve as the non-return valve is on the side. Blocks the flow.

As the refrigerant passes through the expansion valve, the refrigerant expands in volume and becomes a part liquid, part vapor mixture. This volume expansion reduces temperature and pressure. Heat pumps for dummies We have described how thermal expansion valves work and how electronic expansion valves work, click on the links to learn about them. Then the coolant moves the working principle of the rotor oil pump with diagram.

External Heat Exchanger Heat Pumps For Dummies

Here, a fan blows ambient air over the coil and adds heat to the cold refrigerant. Refrigerant boils at a very low temperature, and as it boils it absorbs heat energy.

For example, we know that when water boils it transfers heat energy in the form of steam and it boils at 100*C (212*F), if we look at some common heat pump refrigerants, the boiling point of R134a is -26.3. °C (-15.34*F) and the boiling point of R410A is -48.5 °C (-55.3*F). Hence it is very easy to extract heat energy even at very low outdoor temperatures. We explained how coolers work in a previous video, again the links are below.
So the refrigerant takes heat energy from the outside air, leaves the outside heat exchanger as low pressure, low temperature slightly superheated steam and returns to the reversing valve. The reversing valve transfers it back to the compressor to repeat the cycle.

When the system can switched to cooling mode, the system works like a normal split air conditioner. The compressor sends the high-pressure, high-temperature vapor refrigerant to the reversing valve, where the reversing valve transfers it to the outdoor unit. The outdoor unit fan blows ambient air into the heat exchanger, this air is at a cooler temperature, so it carries away the heat energy of the refrigerant.

Refrigerant condenses Heat pumps for dummies

Refrigerant condenses as it loses its heat energy. It then emerges as a high-pressure, low-temperature liquid refrigerant.

It then goes to the expansion valve, but since it can closed, the refrigerant passes through the non-return valve, the sight glass and the two-way filter drier. Next the non-return valve closes, allowing the refrigerant to pass through the expansion valve. As it passes through the expansion valve, the refrigerant becomes a partly liquid and partly vapor mixture, causing a drop in pressure and temperature.

It flows into the indoor heat exchanger and a fan blows the warm indoor air the cooling coil, which transfers heat from the air to the coolant, causing the coolant to boil and remove this heat. Heat pumps for dummies The refrigerant leaves the indoor unit slightly superheated at low pressure, low temperature and flows into the reverse valve. The valve returns it to the compressor to repeat the cycle.

Air to Water Heat Pump

These units operate in a similar manner but without a reversing valve. The high pressure, high temperature steam leaves the refrigeration compressor but this time goes to the plate heat exchanger. Water can circulated through a hot water storage tank on the other side of the plate heat exchanger.

Cold water enters the heat exchanger from the tank and it passes through the heat exchanger it absorbs heat from the hot refrigerant so it stays warm and the hot water flows back into the storage tank. As the refrigerant releases its heat to the water, it condenses and leaves the heat exchanger as high-pressure, low-temperature fluid. We have described how heat exchangers work in our previous tutorial, click here for a tutorial on heat exchangers.

The refrigerant passes through the filter drier and sight glass into the expansion valve. The expansion valve turns the refrigerant partly liquid and partly vapor at lower pressures and temperatures. It then passes through an external heat exchanger where the outside air boils the refrigerant, the refrigerant exits as low pressure, low temperature slightly superheated vapor and can drawn back into the compressor.
The hot water tank then supplies hot water to radiators, sinks and showers in the building.

Ground Source Heat Pump

There are two main types of ground source heat pumps, horizontal or vertical types. Both work essentially the same way, they differ in how they access heat in the ground. In our next heat pump article we will look at the advantages and disadvantages of different types and when use them, this article will only focus on how they work.

An underground source can used to heat air or water. Heat pumps for dummies In an air type system, the heat pump may have a reversing valve and then provide heating or cooling.

In both cases the external heat exchanger is a plate heat exchanger, refrigerant going on one side and a mixture of water and antifreeze on the other. A mixture of water and antifreeze can  pumped around pipes in the floor. This allows the heating system to take heat energy and bring it to the heat exchanger, the refrigerant on the other side of the heat exchanger absorbs the heat because it has a very low boiling point and carries away the heat as it boils. There is Then it can used inside the building.

Air type systems may have a reversing valve. This will allow the refrigeration system to draw unwanted heat from the building and transfer it to the antifreeze compound. This water can then pumped around pipes in the ground, transferring the heat to the ground, which is cooler and ready to absorb more heat.

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Water Source Heat Pump

Water source heat pumps come in two main types. Closed and open loop. A closed loop takes heat energy from the pool or river and sends it to a heat exchanger. An open loop takes water from aquifer or river and pumps it into a heat exchanger.

A mixture of water antifreeze collects heat energy in a closed loop around the pipes and brings it to a heat exchanger, where the refrigeration system absorbs the energy and uses it for heating. Alternatively, the building’s unwanted heat can  pumped into the antifreeze compound to cool the building. The unit then functions like a ground source heat pump.

In open loop types, water can drawn by a pump and sent directly to the heat exchanger. A heat exchanger extracts heat energy from water or puts unwanted heat back into the water. The water then passes through the heat exchanger and returns to the source located some distance away.

 

 

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