Ventilation

Heat exchanger air - what, why and how to make your own hands?

Air Exchanger - what

Everyone knows that to create in the roomhealthy microclimate necessary ventilation. The room should be clean air to enter from the street, but at the same time removes the same amount of air from the room. In winter, with the outflow of "waste" air permanently out from the premises of value and it is expensive by today's heat, and summer, when only complicates their work in the room is air-conditioned, hot air supply. So, to the literal meaning of the expression is not to let your money away, and was coined by the air heat exchanger.

Content

  • What is it - the heat exchanger?
  • The classification of these devices
    • The rotary type heat exchanger
    • Heat exchanger plate type
  • Air handling unit with heat recovery
    • Functions work tasks
  • Heat exchanger with his hands how to calculate the efficiency of

What is it - the heat exchanger?

The word "heat exchanger" comes from the Latin«Recuperatio», that means the opposite to obtain or return. In our case it is the heat exchanger, the heat energy in the winter returns, flows away from the room with the exhaust air, and in summer prevents the penetration of heat to the supply air.

Since the heat exchanger is arranged, and whathow it works? The concept is fairly simple, and the heat exchanger is a double-walled heat exchanger in which, without mixing two air streams meet - exhaust and supply air. Due to the temperature difference between the air streams are exchanged between the thermal energy, ie, the cold air is heated and cooled by warm. Furthermore, while cooling the warm air is removed from it its moisture due to condensation on the walls of the heat exchanger.

Recovery is, in fact, by reducinglosses through the ventilation system, that is, energy saving technology. With the recovery, you can save more than 70% of outgoing heat. The energy is reused in the same process! There recuperators different capacities and designs.

The classification of these devices

  • Under the scheme of movement of heat carriers (co-current, counter-current)
  • By construction (tubular, ribbed, plate, etc.)
  • By appointment (for heating air, fluids, gases)

The rotary type heat exchanger

Heat recovery rotor

The rotary heat exchanger is characterized by excellent efficiency, the main disadvantage - the large dimensions

Is a short cylinder stuffed tightlypacked longitudinally spaced layers of corrugated steel. Located a rotor in the direction of the axis of the flow-hood. The drum rotates the heat exchanger, first passing through the exhaust yourself warm air, then supply the cool air. There is alternately heating and cooling plates, the heat is given to the incoming cold air. Rotary recuperators are highly efficient, but they are rather cumbersome. For proper organization of supply and exhaust systems required large plenum.

Heat exchanger plate type

Heat exchanger plate

The main disadvantage of plate heat exchanger - frequent freezing air supply side plates located outdoors in winter

Presented cassette, in which the channelspassage of supply and exhaust air are separated by sheets of galvanized steel plates. Streams are not mixed, but the heat transfer is inevitable due to the fact that the plates are heated and cooled simultaneously from different sides.

Plate heat exchanger air (alsocalled cross-flow) is quite common because of the low cost and compact design. But there is one feature - a high probability of frost from the extraction device, if the outside temperature is low enough, due to the formation of condensation in the exhaust ducts.

Figure 1. Plate heat exchanger

Design and operation of the plate heat exchanger

If we evaluate the effectiveness of the plateheat exchangers, the efficiency of such devices - about 60%. Another important feature - a very simple heat exchanger device (without rubbing and moving parts), in such a device does not apply any electricity-consuming elements.

Plate heat exchanger, despite somedisadvantages, namely: frequent freezing of the heat exchanger in the cold season, a mandatory design feature of crossing pipes both ducts in the recuperator, which may be difficult to achieve, the most common device for the supply and exhaust installation in homes, apartments and garages. Freezing of the heat exchanger is achieved by periodical switching the supply fan or the use of a bypass valve.

Along with the factory recuperators widespread use of improvised units, for air heat exchanger do with their hands is not so difficult. Consider a household in the heat exchanger.

As you can see, a self-made heat exchanger can be quite effective.

Air handling unit with heat recovery

Consider ways of arrangement garage ventilation system. Ventilation in the garage can be a natural, mechanical and combined.

  • Natural ventilation - this is when the garage wall breaks a hole for the passage of air, and the ceiling is inserted into the duct for removing "waste" of air.
  • With a combined inflow ventilation leave a natural and complementary to the chimney fan running from the power supply for the forced air.
  • Mechanical ventilation - the most expensive, but at thealso the most effective method of ventilation devices. Air outflow and inflow is carried out compulsorily, it is possible to design different modules for the inflow and outflow of air.

Work units of the mechanical systemagreed, the most expensive unit is a unit providing fresh air supply. The design of such a device is required ventilator, filters, heater. Heat exchanger design brings additional features discussed above.

Functions work tasks

  1. Efficient heat transfer.
  2. Removal of condensate.
  3. High performance.
  4. Quiet

The optimum temperature for the contents of the carduring the cold season 5 degrees, and the use of such air handling unit with heat recovery often replaces the use of the heating system.

Heat recovery with his own hands

If your intention is to make a plate heat exchangeryourself, then you will need to 4m2 galvanized sheet, it should be cut into the plate 20? 30cm and put them in a pile. The plates must be perfectly smooth, so if you are using galvanized, it is more convenient to cut a stack of three sheets grinder than use metal shears. To create a remote gap between the plates can be glued to them the scope of the technical cork strips (thickness 2 mm). Gaps between the plates should not be less than 4 mm, to avoid too much resistance to the air flow. It is important to choose the recuperator section - air flow rate should be equal to or slightly more than 1 m / s. After placing all the stack gap must be filled with a neutral sealant composition.

After drying the sealant plate should beput into the body (any tin box of appropriate size). The housing is made of sheet metal, it makes a hole in which to insert plastic flange diameter must match the diameter of the duct. All slots are sealed with silicone sealant. The box is made of MDF or plywood thickness of 18mm, all the walls insulated with mineral wool. The total area of ​​the plates will be at 3,3m2 performance 150m3 / h, collected in this way should have a heat exchanger efficiency of 50-60%. In winter, when the outside air temperature is below -10 ° C Plate heat exchangers can be covered with ice, so to periodic thawing in warm parts necessary to install a pressure change in the sensor. When frost build-up supply air will flow through the bypass and the heat exchanger begins to thaw warmed by the exhaust air.

Modern home supply and exhaust systemventilation is a must. After a conventional ventilation ducts in the kitchen and bathroom to maintain a healthy indoor climate is not under force. Modern finishing materials are often "not breathing" technology aimed at energy efficiency (the production of plastic windows, for example) allow a virtually airtight room. Additional supply and exhaust system with heat recovery will help to ensure normal ventilation and solve the problem of the development of fungi and mold, which is especially important for wet areas with poor ventilation. Thus, the heat exchanger for an apartment, private house, and all the more so for the garage (excessive humidity in the garage inevitably leads to corrosion, and the exhaust gases and fuel vapors in conjunction with "stale" air harmful to human health) - a very necessary device.

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