Ground source heat pumps, a great source of renewable energy!
Applying a heat pump for heating of houses and the production of hot water is very much growing lately. The technique is very simple: you will extract heat from outside to heat your house on the inside. In Germany and in the Scandinavian countries, this technique is already applied much longer and is an integral part of the design of a home. But also in Scotland there is more and more interest in this alternative heat source. Not at least because of the renewable heat incentive that the UK government only just recently further improved.
A heat pump is basically a refrigerator in reverse. A refrigerator takes the heat from the inside of the refrigerator and extracts heat on the outside of the unit, a heat pump installation extracts the natural heat from the outside of a building to the inside. A heatpump for the House can use heat from the air, the soil or the (ground)water. In the ground the temperature from a depth of 1.5 metres will be more than 0 ° c throughout the year, for example. It is for that reason a great source of renewable energy.
How does a heat pump work?
The current generation of heat pumps are usually based on an electrically powered compression technique. Fluid is being pumped in a closed circuit. This fluid is depending on the pressure and temperature in liquid or gaseous state. It is these changes of state that makes sure that the heat is contained and then issued.
A heat pump installation consists of a fluid circuit pump, expansion valve and two heat exchangers. The evaporator extracts the heat from outside and the capacitor causes the heat again. In steps the following happens:
Step 1: abstraction of heat a liquid with a boiling point lower than the ambient temperature serves as means of transport of the heat. The liquid draws heat to the outside air or other heat source and then evaporated in the evaporator.
Step 2: compression a compressor then expresses the evaporated liquid together. This increases the pressure and the temperature of the vapor.
Step 3: release of heat the collected heat from the vapor is then issued to a boiler deposit through a condenser. Because the vapor cools down again in this barrel condenses this view to liquid. This then flows through the expansion valve (which lowers the pressure and therefore the temperature) to the evaporator with which the process starts again.
Heat pump efficiency
A heat pump is pumping coolant around in a closed circuit. To do this, use the pump gas or electricity. The efficiency of the pump is expressed in the coefficient of performance COP (Coefficient of Performance). This gives the ratio of energy output. A coefficient of performance of 3 means that to three heat-pump units to produce one unit of electrical energy needs. The COP is always greater than 1 you read therefore always have returns higher than 100%. A heat pump is interesting as the power consumption of the pump is more than offset by the won heat (high COP). This rate of return is determined by the difference and the stability of the temperature between the koudebron and the heat source, the efficiency of the heat exchangers and the electricity consumption of the compressor.
Heat from the ground
When a heat pump gets its heat from the ground we speak of a geothermal heat pump. There are two systems that are applied. The heat exchanger that horizontally in the soil of the garden is set and the heat exchanger vertically in deeper soil layers.
Horizontal heat pump
The Sun heats up the Earth and this energy can be recovered by a distribution system that about 70 centimeters below the ground. You have a well insulated House then the available land in the garden about 1.5 times as large as the heating surface. A poorly insulated House has a larger surface area needed to provide sufficient heat from the ground. Take the construction of the garden, roots can damage the pipes of the heat pump.
Vertical heat pump
It is also possible to the pipes vertically in the ground to a depth of 50 to 150 meters. The temperature of the Earth is at that depth later. This heat comes from solar radiation, soil and water from surface water by heating from the Earth’s core. A vertical pump is ideal for residential houses have insufficient space for a horizontal placement of the pipe system. More about heat from the ground
Heat from the air
A Aerothermal heat pump draws heat from the outside air. The evaporator consists of a series of tubes where the coolant flowing through it. These tubes are in contact with the ambient air. The air can flow naturally around (heat exchanger with static air) or supported using a fan. The disadvantage of an air heat exchanger is that it is dependent on the temperature of the air, and as everyone knows these strongly fluctuates. The return (COP) of this air heat pumps varies strongly. As a result, it is usually necessary to combine this system with another heat source in order to be able to jump if not enough heat. More about heat from the air
Heat from water
It is also possible to heat from the groundwater, a pond or even a river. This technique can be interesting because these sources generally a relatively stable temperature can deliver what benefits the return. However, it is not in every situation possible. Heat exploit with heated floors and Wall heating You can won the heat with a heat pump in different ways. The theory is that the lower the temperature used is the more efficient the installation works. In other words, the smaller the difference between the koudebron and the heat source the higher the return. Low temperature heating is widely applied through floor heating and wall heating. Underfloor heating by the large surface area for even temperature distribution whereby at much lower temperature can be fired while maintaining comfort. Heating using a heat pump is the most suitable for new homes. From the beginning can take into account the situation and choose the most efficient system. In most cases, this means excellent insulation in combination with low temperature floor heating. For existing construction is a heat pump installation only interesting at rigorous alterations.