Heat is one of the most sought-after types of energy required to sustain human life. At the same time, the resource costs for its production are quite impressive - whether it is electricity with petroleum products or traditional fuels like coal and wood. Obviously, against this background, there is a need to offer an alternative method of heating. One of the most promising and actively developing technical solutions of this type is a geothermal heat pump, the concept of which is gradually approaching domestic operating conditions.
Technology overview
Any idea of an alternative source of heat involves the service of one or another natural material or phenomenon. In this case, the subsoil is the central energy supplier. Ground on certaindeep enough to maintain a sufficient temperature so that its heat can be accumulated and further used on the surface. Hydrological resources can also be considered as a source of heat, making adjustments to the technical design of the storage infrastructure.
To represent the effectiveness of this technology, it can be noted that when investing 1 kW of energy in the maintenance of a geothermal heat pump, you can get a return in the form of 2-6 kW. What explains such a high efficiency? Compared to other means of processing natural energy sources, geothermal mechanisms do not provide for intermediate conversion steps. For example, solar energy storage requires light and heat to be converted into electricity, which is used to run the house. In this case, the heat is not converted, but directly or with minimal transitional steps is transferred to the target consumers.
Operation principle
To begin with, it is worth identifying specific points that are involved in the process of geothermal heating. The process begins in the ground - at a level that is located below the freezing point. The temperature may vary depending on the depth. For a minimum thermal effect, it is enough that it exceeds 0 ° C, but in practice 35-40 ° C is considered an economically justified indicator. The end user is the heating circuit.
A special pipeline is responsible for transferring energy from the ground to the home heating system,serviced by a geothermal heat pump. The principle of operation is based on the fact that heat is transferred through this supply line with an evaporator heat exchanger along the refrigerant circuit. As in air conditioners, freon plays the role of the active evaporating substance. Before the start of the pump, it is in a liquid state, and after start-up it passes into a gaseous form. Further, the updated refrigerant is transferred to the compressor, the communications of which are connected with the final heating circuit. Excess freon at this point is discharged through the outlet channel.
Geothermal Equipment
The main functional element of the system is a thermal mechanical pump. The structure of the unit is represented by three circuits:
- External. Circulates conventional coolant in the form of antifreeze or brine.
- Internal. Contains refrigerant in sealed chambers where heating-evaporation processes take place.
- Outer loop that goes directly to the target served system.
Also, the list of working bodies of a geothermal heat pump for heating includes a compressor, an evaporator, a discharge channel and heat carriers. It is important to note that designs, layout and additional functionality may vary depending on the application. There are installations for soil, for water and air, as well as combined systems that can work in different conditions.
Heat sources and storage facilities
Geothermal systems have many advantages,associated with economical energy supply, practicality and technological accessibility for domestic use. But, like other systems that store alternative energy, it is dependent on the source. Therefore, in order to be sure of the stability of heat supply, it is necessary to think over in advance the possibility of connecting to a backup energy supply channel. Ground and hydrological sources will be discussed below, but for now, you should familiarize yourself in principle with the working infrastructure that the geothermal heat pump serves as a resource supply system. Bulk materials, pipes, probes and structures, the structure of which can accumulate energy, act as heat receivers. In particular, these can be heating mats associated with a pump, coolant and third-party heating systems.
Ground source of thermal energy
High-capacity systems that store geothermal energy are placed in fields of about 200 m22. A layer of soil 40-50 cm thick is removed from the marked zone below the freezing point. In general, a thickness of 150-200 cm is obtained. These and other data are indicated in the project with the calculation of energy volumes for a particular heating circuit. Much will also depend on the region, since in one area you can extract 30 W from 1 m2, and in another - 70-80 from 1 m2.
Wells, trenches or solid platforms are formed on the site to accommodate accumulating elements. The most accessible in implementation is considereda vertical downhole installation in which spiral accumulation pipes or mats are placed. In a horizontal configuration of the intake infrastructure, a ground source heat pump for heating can produce large amounts of energy, but it has disadvantages. They relate to the complexity of earthworks (requires special equipment to develop large areas), the exclusion of any landscaping and lower temperatures by the end of the heating season.
Water source of thermal energy
The main objects of service in this case are lakes, reservoirs and ponds. As for the accumulating elements, their function is performed by polymer pipes with antifreeze filling. The volume of extracted energy on average can be represented as 30 W per 1 m of pipe. For complex maintenance of a large private house, 12 kW is required - accordingly, it is necessary to organize a piping system 400 m long.
There is another approach to heat storage from hydrological resources. If there are no lakes and reservoirs nearby, then on your own site you can equip 2-3 wells with wells with a depth of about 20 m. The water at this level will have a temperature of about 10 ° C, but this is enough for the auxiliary heating function. The bottom line is that a ground source heat pump performs the task of constantly circulating warm or hot water. On one side of the circuit, the resource is constantly heated in the wells without the slightest cost, and the house accumulates energy from the newly received portion of water.
Geothermal system installation
Before making a decision to purchase equipment, it is necessary to assess how justified the use of this technology is in principle in a particular region. To do this, a number of geological exploration studies are carried out with the determination of the depth of soil freezing.
In the installation, pipes or other accumulating elements, a pump and installation fittings are involved. The internal heating infrastructure can be formed by radiators, fan coolers or a warm water floor, etc. This will be the system for consuming the supplied resource.
So, geothermal heat pumps are installed for the house in wells - as already noted, not only land, but also water. It is possible to equip wells, trenches and fields with a liquidated layer of soil, but this option is more often used for industrial heat supply. In the created niche, batteries are laid throughout the site - in a straight-line or spiral configuration. The circuits are connected to a pump located on the surface, which, in turn, is connected to domestic heating circuits.
Geothermal pump manufacturers
The segment is being actively developed by the efforts of the largest developers of HVAC equipment. In particular, the boiler manufacturer Viessmann presents reliable units for water and ground heat storage at an operating temperature of around +65 °C. For industrial and public buildings with an area of 300-350 m2 the NIBE F1145 ground source heat pump is available. To hisfeatures include the ability to connect to a three-phase network at 380 V, and a single-phase network at 220 V. The Japanese company Mitsubishi offers universal models of geothermal pumps in terms of applications. The developers of this company have been developing the concept of multi-zone heating separation with a simplified control system since 2007.
Do not ignore such a promising segment and domestic companies. For example, a Russian-made BROSK Mark II 100 geothermal heat pump is designed specifically for a private consumer - the owner of a small country house. But, despite the modest performance, this equipment is characterized as reliable, energy efficient and multifunctional.
Positive feedback on technology
This method of heating attracts many people with the convenience of maintenance, maintenance and, of course, minimal financial costs during operation. The equipment practically does not require consumable fuel materials. Electric resources are needed to ensure the function of the same pump and control equipment, but they are insignificant against the background of the amount of energy returned. The environmental friendliness of geothermal heat pumps is also emphasized. Reviews and at all one of the first places among the pluses put the fact that the working infrastructure does not take up space in the house. Only communications are brought in, and the rest of the functional units and nodes remain on the street.
Negative reviews
With a full-fledged boiler room geothermal thermal performancesystems are not comparable. And the point is not even in specific power indicators, but in the spasmodic supply of heat. Many complain about long periods of low energy delivery rates, which is why it is recommended to organize backup supply systems. But there is another shortcoming here. Although a little money is spent on the maintenance of the equipment, the initial investment is comparable to the purchase of a powerful industrial boiler. Even a geothermal heat pump of Russian origin BROSK Mark II 100 is available on the market for 250-300 thousand rubles. depending on the configuration. Installation costs will also cost 50-70 thousand rubles.
Conclusion
There are quite a lot of options for organizing heat supply in a private house. Each of them is expensive in its own way during operation - from expensive electrical panels to economical gas boilers. But, traditional equipment in a modern design is a system that is optimized in design and easy to manage. What can attract a geothermal heat pump for home heating? Of course, the economic factor will come to the fore, but what else? You can turn to such installations if there is enough space on the site to organize the complex. In this case, you can count on at least passive auxiliary space heating without constant monitoring and maintenance. And one more thing - this is complete autonomy, allowing the use of geothermal equipment as a backup source of heat.
