Heat is one of the most sought-after types of energy required to maintain human life. Moreover, the cost of resources for its production is quite impressive - be it electricity with petroleum products or traditional fuel like coal and wood. Obviously, against this background, there is a need to propose an alternative heating method. One of the most promising and actively developing technical solutions of this type can be attributed to 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 maintenance of a natural material or phenomenon. In this case, the central energy supplier is the subsoil. Soil at certain depths maintains a sufficient temperature so that its heat can be accumulated and subsequently used on the surface. Hydrological resources can also be considered as a source of heat, making their own adjustments to the technical performance of the storage infrastructure.
To represent the effectiveness of this technology, it can be noted that when 1 kW of energy is invested in the content of a geothermal heat pump, a return of 2-6 kW can be obtained. What explains such a high efficiency? Compared to other means of processing natural energy sources, geothermal mechanisms do not provide for intermediate stages of conversion. For example, the accumulation of solar energy requires that light and heat be converted into electricity, which is spent on the maintenance of the house. In this case, heat is not converted, but is transferred directly or with minimal transitional stages to the target consumers.
Operating 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 below the freezing point. The temperature may vary depending on the depth. For a minimum thermal effect, it is enough to exceed 0 ° C, but in practice, 35-40 ° C is considered an economically viable indicator. The final consumer is the heating circuit.
A special pipeline, served by a geothermal heat pump, is responsible for the transfer of energy from the soil to the home heating system. The principle of operation is based on the fact that heat is transferred through this refrigerant-evaporator supply line along the refrigerant circuit. As in air conditioners, the role of the active evaporated substance is played by freon. Before the pump starts, it is in a liquid state, and after starting it goes into a gaseous form. Next, the updated refrigerant is transferred to the compressor, the communications of which are connected with the final heating circuit. The excess freon at this point is discharged through the bypass channel.
Geothermal equipment
The main functional element of the system is a heat-mechanical pump. The structure of the unit is represented by three circuits:
- External. It circulates a conventional heat carrier in the form of antifreeze or saline.
- Interior. Contains refrigerant in sealed chambers in which heating-evaporation processes occur.
- An external circuit that is directly routed to the target system being served.
The list of working bodies of a geothermal heat pump for heating also includes a compressor, an evaporator, a discharge channel and coolants. It is important to note that the design, layout and additional functionality may vary depending on the conditions of use. There are installations for soil, for water and air, as well as combined systems that can work in different conditions.
Sources of heat and means of storage
Geothermal systems have many advantages associated with the economical supply of energy, practicality and technological accessibility for domestic use. But, like other systems that accumulate 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 in advance about the possibility of connecting to the backup channel of energy supply. Soil and hydrological sources will be discussed below, but for now, you should familiarize yourself with the working infrastructure, which the geothermal heat pump serves as a resource supply system, in principle. Bulk materials, pipes, probes and structures, the structure of which can accumulate energy, act as heat receivers. In particular, it can be heating mats associated with the pump, coolant and third-party heating systems.
Soil heat source
High-performance systems that store geothermal energy are located on fields of about 200 m 2 . A soil layer 40-50 cm thick lower than the freezing point is removed from the marked area. 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 depend on the region, as in one area you can extract 30 watts from 1 m 2 , and in another - 70-80 with 1 m 2 .
Wells, trenches or continuous platforms are formed on the site to accommodate the storage elements. The most affordable in the implementation is considered to be a vertical well installation, in which spiral accumulating pipes or mats are placed. In the horizontal configuration of the intake infrastructure, a geothermal heat pump for heating can produce large amounts of energy, but it has disadvantages. They relate to the difficulty of excavation (special equipment is required to develop large areas), the exclusion of any landscape work and lowering the temperature by the end of the heating season.
Water source of thermal energy
The main objects of service in this case are lakes, ponds and ponds. As for the accumulating elements, their function is performed by polymer pipes with antifreeze filling. The volumes of extracted energy on average can be represented as 30 W with 1 m of pipe. Comprehensive maintenance of a large private house requires 12 kW - accordingly, it is necessary to organize a pipeline system 400 m long.
There is another approach to the accumulation of heat 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. 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 geothermal 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 at no cost, and the energy from the newly received portion of water is accumulated in the house.
Installing a geothermal system
Before making a decision on the purchase of equipment, it should be assessed how, in principle, the use of this technology is justified in a particular region. For this, a number of exploration studies are carried out with the determination of the depth of freezing of the soil.
The installation involves pipes or other accumulating elements, a pump and installation accessories. Radiators, fan coolers or a warm water floor, etc. can form the internal heating infrastructure. This will be the consumption system of the supplied resource.
So, geothermal heat pumps are installed for the house in the wells - as already noted, not only land, but also water. You can equip wells, trenches and fields with an eliminated soil layer, but this option is often used for industrial heat supply. In the created niche, the batteries are stacked throughout the site - in a straightforward or spiral configuration. The circuits are connected to a surface-mounted pump, which in turn is connected to home heating circuits.
Manufacturers of geothermal pumps
The segment is actively developing by the efforts of the largest developers of HVAC equipment. In particular, the manufacturer of boilers Viessmann presents reliable units for water and ground heat storage at an operating temperature of about +65 ° C. For industrial and public buildings with an area of 300-350 m 2 , the NIBE F1145 geothermal heat pump is offered. Its features include the ability to connect to a three-phase network of 380 V, and a single-phase network of 220 V. Universal from the point of view of the application models of geothermal pumps offers the Japanese company Mitsubishi. Since 2007, the developers of this company have been developing the concept of multi-zone heating separation with a simplified control system.
Do not ignore such a promising segment and domestic companies. For example, a Russian-made geothermal heat pump BROSK Mark II 100 is designed specifically for a private consumer - the owner of a small country house. But, despite its 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, with minimal financial costs during operation. The equipment practically does not require fuel consumables. Electric resources are needed to provide the function of the same pump and control equipment, but they are insignificant against the background of the returned amount of energy. The environmental cleanliness of geothermal heat pumps is also emphasized. Reviews do put one of the first places among the pluses that the working infrastructure does not take up space in the house. Only communications are summed up, and the rest of the functional units and nodes remain on the street.
Negative reviews
With a full boiler house, the thermal performance of geothermal systems is still not comparable. And the point is not even in specific power indicators, but in spasmodic heat supply. Many complain about long periods of low levels of energy delivery, which is why it is recommended to organize backup supply systems. But here is another flaw. Although a little money is spent on the maintenance of the equipment, the initial investment is comparable to buying 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 a lot of options for organizing heat supply in a private house. Each of them is in its own way costly 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 heating a house? Of course, the economic factor will come to the fore, but what else? You can refer to such installations if the site has enough space for the organization of the complex. In this case, you can count on at least passive auxiliary heating of the premises without constant monitoring and maintenance. And one more thing - this is complete autonomy, allowing you to use geothermal equipment as a backup heat source.