DE2601127A1 - Air conditioning system with waste heat recovery - has heat exchangers in air vent and outside air conduits linked with refrigerating compressor - Google Patents

Abstract

The air conditioning system has heat exchangers to recover waste air heat. Both the waste air vent conduit and the outside air conduit have fitted coolant air heat exchangers which are linked by a reversible flow coolant circuit with a refrigerating compressor. The exchangers are finned tubes with a small pressure gradient on the air side. The compressor forms a single unit together with the outside air heat exchanger and air treatment components such as the weather grid, feed air filter and fan preheater.

Description

Air conditioning system with heat exchangers, especially for return

extraction of exhaust air heat.

The invention relates to an air conditioning system with heat exchangers, in particular for the recovery of exhaust air heat.

To utilize the waste heat contained in the exhaust air from any room regenerative or recuperative systems are already being used.

In a known regenerative heat exchanger, special Air duct the exhaust air heat is stored in a finely corrugated asbestos cardboard mesh and released from it to the outside air drawn in. The heat transfer medium is permeable to air with a relatively high air-side resistance of 15 to 20 mm rS. Exhaust air duct and outside air duct must be led directly past each other; the Tt heat carrier mass is applied to a wheel that is rotated slowly and thus the stored Releases heat from the exhaust air duct on the other side to the outside air duct (Heating-Ventilation-Haustechnik 1969, pp. 110-112).

Disadvantages of this regenerative system, which is both tactile and latent heat (i.e. air humidity) is able to transfer, are the danger of Bacteria transfer through the humid air, the accumulation of germs in the hygroscopic Material, the odor transmission in odor-intensive exhaust air flows as well as the Abrasion of the heat storage mass, which is 200 fibers per cbm of air with etisa.

With these disadvantages, the use of these is otherwise very economical Heat exchanger not possible with special hygienic requirements on quality the outside air or with odor-intensive exhaust air, such as B. in kitchens, dining rooms, Chicken or French fries roasters, etc.

In addition, because the exhaust air and outside air flows directly past each other have to be, which is often spatial, especially in hospitals and large kitchens and not permitted due to the risk of mixing between outside air and exhaust air the regenerative heat exchanger cannot be used in these systems.

In a known recuperative heat exchanger, glass or metal plates are used or pipes for heat exchange between outside air and exhaust air. Here is the Outside air is separated from the exhaust air, but the use of energy is special with smaller temperature differences between outside air and exhaust air low (system Happy).

Here, too, must because of the necessary direct thermal contact The outside air duct and the exhaust air duct are run side by side with the same Difficulties as described above.

Both systems require little energy for theirs drove; However, they require conventional heating and cooling systems and, when considering their viability, must be related to the fossil fuel-operated heating systems and the cooling systems, mostly with piston chillers, cold water circuits and cooling water circuits as well as recooling towers with an open water circuit, fresh water loss and the heat and moisture pollution of the environment be seen.

In rooms with a high proportion of pollutants (operating theaters, kitchens, chicken and French fries fryers, battery rooms, etc.) is supported by guidelines and standards (DIN 1946, sheet 4) mostly pure outdoor air operation all year round or a high outdoor air rate required for the ventilation or air conditioning system. The warming up of the large amounts of air in winter and also the cooling of this amount of air in summer requires an enormous Energy expenditure. Because of the special hygienic requirements, the known Heat recovery systems are not used in these systems.

The invention is based on the object of providing an air conditioning system of the initially introduced named type for the hygienically perfect utilization of the exhaust air heat from rooms with polluted exhaust air or rooms with special hygienic requirements to create the outside air that enables summer / \ Jinter operation in his Energy expenditure is at least equivalent to the systems described, simply to waiting and allows separate routing of exhaust air and outside air ducts.

This task is solved according to the invention in such a way that in the exhaust air duct and a refrigerant-air heat exchanger is arranged in the outside air duct and the two heat exchangers through a reversible refrigerant circuit in its flow direction connected to the / refrigeration compressor is switched on. Of the Heat is only transported via a refrigeration circuit with a direct evaporator and condenser, both as refrigerant-air heat exchangers. The heat transfer medium is a refrigerant e.g.

Frigen 22 or Frigen 12. Another heat transfer medium, such as water or Brine with the inevitable losses at the heat exchangers is not required. In a manner known per se, direct evaporator and condenser can be used in the refrigeration circuit can be switched by valves, so that the compressor either the outside air and the exhaust air cools down (Xfinter switch) or vice versa (summer switch). The system works with the usual coefficient of performance of 4 to 5 for heat pumps, i.e. that for the transfer of 1 KW of energy from the exhaust air to heat the outside air only a drive power of the compressor of 250 or 200 watts is required.

In summer operation, the evaporator is switched to the outside air, so that it enters the rooms pre-cooled.

In these cases, the condenser is switched to the exhaust air and heats them up just like with conventional air-cooled condensers without enrichment the humidity of the exhaust air. There is contact between the outside air and the exhaust air this combination does not take place at any point.

While the outside air heat exchanger along with all the other required Elements of the supply air preparation and the heat pump circuit, such as weather protection grille, tLouvre damper, supply air filter, preheater and supply air fan as well as the refrigeration compressors can be delivered and installed as a compact device in a factory-tested unit the exhaust air heat exchanger is in an exhaust air device together with the exhaust air fan and corresponding flaps or protective grilles at any other point in the building that is favorable for exhaust air discharge at a distance arranged up to 50 m.

The heat exchangers for outside air and port air are depending on the hygienic Requirements from the T.; 7 materials copper, aluminum, copper-aluminum with plastic coating, Made of copper-copper, galvanized steel or stainless steel. If required, can flush at any time as an automatic interval cleaning without disassembly carried out, whereby e.g. odorous substances, that would pollute the environment can be washed out. Interchangeable flilter knitted fabrics in a cleanable version or as a disposable filter, can be used for degreasing and removal the exhaust air can be switched on.

The arrangement according to the invention increases the economy of the pure Outside air systems or the systems with a high proportion of outside air with a high proportion of outside air at the same time hygienic requirements considerably due to the elimination of various heat transfer media as well as the corresponding power take-offs and the utilization of the high performance figure known heat pumps.

In the following the invention is applied to a heat recovery system explained for a large kitchen.

The drawing shows a complete ventilation system for a kitchen pure outdoor air operation. For heat recovery if the corresponding In accordance with hygienic requirements, the system is designed as a heat pump circuit.

The outside air is at a convenient point on the side wall of the building the weather protection grille 1 and the louvre flap 2 as well as the filter 3 sucked in.

A preheater for Tjarmwasser 4 is used to cover peak loads very low outside temperatures. The heat exchanger 5 is connected to the refrigerant circuit connected; it serves as a heater (condenser) in winter and as a cooler in summer (Evaporator).

The heat exchanger 5a belongs to the second refrigeration cycle, which is not The air flows over the droplet separator 6 and the Supply air fan 7 through the outside air duct into the supply air ceiling for the kitchen. Of the Compressor 8, 8a with refrigerant collector is operated in a heat pump circuit.

The temperature sensor for the temperature control device is located in the kitchen 9.

The exhaust air device can be installed at any distance up to 50 m from the Open air device removed in a convenient place for the blow-out in vibration-free Be arranged in the building. It contains the exhaust air fan 10, which is arranged in front of the heat exchanger 11 or 11a, so that its heat dissipation as well is still being exploited. via the louvre flap 12 and the weather protection grille 13 the exhaust air is conveyed into the open air so that it does not mix with the outside air can take place.

In summer operation, the compressor 8 pushes through the position I / II of the Switching valve 15 a gaseous refrigerant in the exchanger 11 in the exhaust air duct, where this condenses and gives off heat. The pressurized liquid Refrigerant is pumped into the heat exchanger 5 via the expansion valve 16, whereby it evaporates and removes heat from the outside air. That which is under low pressure Gaseous refrigerant is now released via position IV / III of the switchover valve 15 sucked in again by the compressor.

In @interbetireb the switching valve 15 is according to I / IV, II / III switched so that the exhaust air is cooled and the outside air is heated. Of the Controller 14 controls the corresponding processes and switches the preheater 4 with it on if the heat pump's heating output is insufficient, as this is economical Reasons expediently on the cooling capacity requirement and thus also on the heating capacity requirement is dimensioned at an outside temperature of -3 ° C.

Claims (3)

Claims 1. Air conditioning system with heat exchanger, in particular for Recovery of exhaust air heat, characterized in that in the exhaust air duct and a refrigerant-air heat exchanger (5, 11) is arranged in each case in the outside air duct and the two heat exchangers by a refrigerant circuit reversible in its flow direction are connected, in which a refrigeration compressor (8) is switched on. 2. Air conditioning system according to claim 1, characterized by the use of finned tube heat exchangers with low air-side pressure drops. 3. Air conditioning system according to claim 1 or 2, characterized-Kältenet, that the / compressor (8) with the outside air heat exchanger (5) and the devices for supply air treatment, such as weather protection grille (1), supply air filter (3), supply air fan (7) and preheater (4), is combined into one structural unit.