Recuperation is ... Heat Recovery

Ventilation systems in the latest versions are no longer limited to a standard set of functions, the main one of which is to update the air environment. For example, due to the use of process filters, the equipment minimizes the content of harmful particles in the room, and also prevents odors. Ventilation systems are also being improved in terms of microclimate regulation, which is particularly beneficial from the point of view of energy saving. To ensure this possibility, supply and exhaust units with recuperation of air flows are used. The operation of such systems is based on the processing of heat flows that pass through the elements of the air handling unit. As a result, the user receives not only fresh, but also naturally heated air.

What is the principle of recuperation?

The process of recuperation occurs against the background of interaction of air currents with different temperatures. That is, heated streams give off their heat to cold, thus forming an optimal temperature balance. In ventilation systems, recuperation is the transfer of heat to fresh air, which is carried out in a special heat exchanger. There are different levels of efficiency of this process. For example, an open window shows zero efficiency. In this case, the supply air flows do not heat up, but lower the temperature of the air in the room itself. We can say that this is a process that is the opposite of recuperation.

The average level of efficiency varies in the range of 30-90%. The optimum figure reaches 60%, and systems that show a figure above 80% are considered the most productive. The most effective heat recovery is the heat exchange process, where the heating of the incoming streams will reach the level corresponding to the air being removed. But even modern technologies do not allow achieving 100% efficiency.

Recuperator in the ventilation system

The principle of recuperation is realized in the ventilation system in the form of a surface heat exchanger. The process of heat distribution itself is carried out by means of a wall that separates two oppositely directed flows. The regenerators have a similar device, however, the recovery system differs in that the air handling channels remain the same throughout the whole period of operation. I must say that the climate equipment can serve not only the air environment. And recuperation is also used in work with gas, liquids, etc. There are also different schemes of structural execution. The most common are ribbed, tubular and lamellar models. At the same time, different approaches are envisaged for the design of flow channels, for example, one can single out flow, counterflow and cross devices.

Cross-plate recuperator

In such installations, membrane septa are usually used, due to which effective recovery is ensured. The peculiarity of the system is that, as the air is removed, excess moisture also enters the street. The supply-and-exhaust system with recuperation is also characterized by frost resistance, which is achieved without special heaters. This advantage makes it possible to use equipment with a cross-membrane design in conditions of a temperature regime down to -35 ° C.

Use such facilities and in the provision of residential buildings, and in warehouses, where maintenance is expected of large areas. They also became widespread in agriculture - for example, in the arrangement of poultry houses, vegetable stores and livestock farms. Since heat recuperation in cross structures with membranes also allows for effective cooling in summer, this system also has a demand in the manufacturing sector.

Orebrene Plate Systems

The device of this recuperator provides for the presence of finned thin-walled plates made by high-frequency welding. Metal panels form a structure with the alternate arrangement of partitions rotated by 90 degrees. Due to such a scheme, a high temperature of the heating medium, a minimum level of resistance, and an optimum ratio of the area of the tele-transmitting surface to the weight of the heat exchanger are achieved. In addition, air-handling units with heat recovery with brushed plates are distinguished by their durability and low price. Practice of use confirms that such systems allow saving about 40% of thermal energy. That is, heating costs are minimized, since fresh air is effectively heated by the removed streams.

Rotary models

The features of such installations include low cost and fairly high performance. Although, in terms of indicators of fresh air heating, this option is inferior to the plate structure with a double cassette. Despite the simple configuration of the working elements, the rotary recovery unit sins with a non-ideal distribution of air flows. There is a certain risk that clean air will mix with the removed air and eventually the quality of ventilation as such will suffer. The disadvantages of such systems include the need for frequent maintenance, which is especially disadvantageous when used in residential premises. However, the heating process itself is quite effective.

Direct-counterflow systems

A feature of recuperators of this type is a tubular structure, the elements of which are represented by thin-walled welded elements. In the process of operation of this type of installation, a wall vortex is formed, which increases the heat exchange, but at the same time it breaks down as the resistance in the air channel increases. Most often, such systems are used in the industry, where delicate heating of one of the working media is needed. Also, the direct-flow-counter-current equipment is used in engineering for the dispersion and utilization of heat. Demand and household air-supply plant with recuperation of this type - it is recommended to install in rooms with sealed metal-plastic windows, as well as in ecological houses.

Such recuperators, as a rule, integrate into a single airway casing, which during operation provides low power consumption, compact dimensions with the possibility of flush mounting, high performance and reliability of equipment.

Recuperators for energy efficient houses

The very concept of ventilation systems, in which passive heating of fresh air is provided, is aimed at reducing heating fees. But in terms of equipping energy-efficient houses, recovery is also an environmentally friendly way to normalize the microclimate. Manufacturers produce special ranges, which use safe and effective materials in terms of recovery. In particular, the latest models receive three-stage heat exchangers made of nonporous ultra-thin membranes. Such a device allows to refuse electric air heaters.

In addition to uniform heat transfer, such devices also work effectively with humidity. They provide a complete return of moisture to the room with the complete exclusion of capacitors. As a result, ventilation with recuperation gets rid of the need to install drainage drainage systems.

Automation for recuperators

Developing supply and exhaust heat accumulators and in the direction of the electronic filling. In order to optimize the distribution of flows, manufacturers supply the facility with the possibility of automatically adjusting the position of the inter-channel partitions. In more advanced models, it is also planned to adjust the speed regimes, display temperature indicators and control the degree of contamination of the filters with signaling. In addition, modern ventilation with recuperation provides the ability to control an external duct heater without connecting to the process of third-party devices. That is, in this case, additional heating of the air to an optimum value is ensured.

Filters in recuperators

Like all modern ventilation systems, models with recuperation involve the inclusion of cleaning devices in the design. Since heat transfer involves the maximum reduction of outgoing and injected air flows, the filters in this case play a particularly important role. Most often, the filters themselves use filters of the type F7, which exclude the passage of particles of 0.5 μm in size. G3 coarse filters are less common, but depending on the design, such an addition may be required. For convenience in maintenance, the recovery system is often supplied with filters made of plastics and special fibers - these elements are easy to wash and shake out. As already noted, modern models are also equipped with indicators that determine the time for the replacement of the filter.

Benefits of recuperators

Technologies that are used in the supply and exhaust systems of recuperation, minimize energy consumption and improve the ergonomics of climate equipment. In practice, the user of such an installation can feel and improve the performance of the microclimate. Of course, heat recovery is not as effective from the standpoint of heating function as special heating units, but its operation does not require additional consumption of energy resources. The inclusion of auxiliary heating in the system allows you to balance both the increase in the temperature regime and the savings in energy costs. In general, according to the calculations of specialists, the use of recuperation makes it possible to reduce heating costs by 10-15%.

Disadvantages of recuperators

Such systems have two serious drawbacks. First of all, this is the icing of heat exchangers in winter. For this reason, many users complain about the failure of the equipment in the first weeks of operation in the conditions of frost. However, manufacturers are trying to improve the protective qualities of equipment, supplying installations with thermal accumulators and strong fans. The second disadvantage of the supply and exhaust units with recuperation is their noisy operation. This is especially evident in rotary models. At the same time, developers strive to provide new models with improved means of isolation, so there are low-noise options on the market.

What to consider in choosing a unit with recuperator?

A consumer who has decided to install such a system in his home should focus on system performance, design performance and functionality. Thus, the performance indicator determines the possibility of ventilation in a particular area. Equally important is the design in which the equipment is made. For example, a heat recovery unit with tubular elements makes it convenient to carry out installation with minimal requirements to the free space. As for the functionality, it also affects the ability to regulate the indoor climate performance, and the ergonomic characteristics of the system.

Conclusion

The operation of traditional ventilation systems does not give a hint of an energy-saving function. As a rule, these are gluttonous massive installations that make a significant contribution to increasing the cost of maintaining a house. Against this background, recovery is an almost revolutionary approach to the production of climate equipment, which presupposes the rational use of already used heat energy. If in the typical system air heating is realized as it enters the room with the help of heating equipment, the recovery allows initially to increase the temperature of incoming flows without connecting special heaters. Of course, such installations have their shortcomings, but with them the producers are conducting a fruitful struggle, improving the designs of recuperators.