FI73067B - VENTILATIONSSYSTEM. - Google Patents

Description

T1, .......,. and 73067

The present invention relates to an air conditioning system, in particular for rooms with significant heat and humidity loads, which system comprises devices for recovering heat.

Typical spaces with significant heat and humidity loads include livestock shelters and other livestock shelters, although the invention is also applicable to other spaces with similar conditions.

Traditionally, livestock shelters are not equipped with air conditioning and / or heating devices, as the animals themselves are able to generate enough heat even in winter to maintain a tolerable temperature, which is usually about 0 ° C to + 5 ° C. Such "natural" conditions lead to serious disadvantages in that the moisture in the air condenses both on the internal structures of the protection, which shortens their service life, and in the form of fog, which makes the working conditions uncomfortable and unhealthy. Furthermore, it follows from the low temperature alone that much of the energy received by the animals through food is used to keep warm, which is why the output of the animals decreases considerably.

To improve the conditions, air-conditioning systems have been developed which are generally based on the removal of the moisture produced by the animals, i.e. the moisture load, with the ventilation air. Experience has shown that certain standards have been set for the amount of ventilation air, and since air at very low temperatures has a very limited ability to absorb moisture, these standards dictate ventilation so intensely that equipment, installation and operating costs become appreciable.

In order to reduce heating costs, it is still known to recover heat from ventilation air by means of heat exchangers 35 which transfer heat to fresh supply air. Although a seemingly large part of the heat contained in the blown air has been able to be recovered, the overall economy of 2 73067 has remained unsatisfactory due to the very large volumes of air drawn in and blown out. In addition, the actual amounts of heat transferred to the supply air have been low per unit of air, as the heat exchangers tend to freeze in cold weather, resulting in severe malfunctions or even complete clogging of the system. This problem is particularly difficult when using conventional cross-flow type plate heat exchangers. Especially after clogging of the system, the conditions in the animal shelter quickly become practically intolerable when fog is formed and the concentration of carbon dioxide and other contaminants increases. Due to the high carbon content alone, the output of most livestock will fall significantly.

15 Air conditioning systems of the above-mentioned level are described, for example, in Soviet inventors' certificates No. 909462 and No. 976862, Finnish Patent Publication No. 62413 and German Patent Publication Nos. 2509038 and No. 2637230. Despite the fact that ventilation and heat recovery have continued to exist, a large number of animal shelters without any kind of ventilation system, a fact which illustrates the shortcomings of known systems.

The object of the present invention is to provide a new air conditioning system which eliminates the disadvantages of the known systems.

To achieve this object, an air conditioning system is disclosed, which is mainly characterized in that when the heat recovery is required, the air temperature is kept above the normal value, preferably so high that the exhaust air can absorb at least substantially the humidity load of the room to be air-reduced. from the need to remove harmful gases, in order to increase heat recovery and thus reduce energy consumption, and to increase heat recovery when the moisture absorption capacity of the exchange air at low ambient temperatures becomes insufficient, -5 preserves are recycled back to said space mixed with fresh fresh air. In this way, it is possible to enhance heat recovery, usually at an outdoor temperature of about -10 ° C to -15 ° C.

The heat of the exhaust air is recovered in a manner known per se by means of a heat exchanger. This heat exchanger preferably has at least substantially vertical channels as heat exchanger surfaces, whereby the condensate flow keeps the heat exchanger clean.

Above, as in the following, the term "ventilation air" 15 means air blown into the outside air, while the term "exhaust air" means air leaving the actual air-conditioned space; part of the exhaust air may be recirculated air. The term "need for respiration" refers to concentrations of carbon dioxide and related pollutants.

Unlike previously known air conditioning systems, the present invention is based on the realization that e.g. by raising the temperature of the cattle shelter to a seemingly unnecessarily high value, preferably to about + 13 ° C to + 17 ° C, and reducing the actual ventilation flow to meet only the cattle shelter's indoor ventilation needs. Contrary to the general perception hitherto, it is possible to increase the efficiency of heat recovery to the extent that the air-conditioning system is self-sufficient at outdoor temperatures as low as about -25 ° C and at the same time a stable moisture content and otherwise favorable conditions can be maintained in the livestock shelter.

The humidity of the hot exhaust air has a considerable amount of latent heat and due to the high temperature the condensing phase of the exhaust air in the heat exchanger is prolonged, whereby the La-35 exam heat is largely recovered, which contributes to the economy of the air conditioning system.

The invention further achieves a greater thermal difference between the internal temperature and the freezing point of the water. This allows more economical heat exchanger solutions to be used and reduces the risk of freezing.

The invention will now be described in more detail with reference to the accompanying drawing, which shows an embodiment of the invention in the form of a flow chart.

In the drawing, arrow 1 indicates fresh supply air, arrow 2 indicates air to be blown into the space to be ventilated, e.g. cattle shelter, arrow 3 indicates il-10 land leaving the space, part of which is recirculated air, arrow 4, and the rest is ventilation air blown into the outside air, arrow 5 .

Reference numeral 6 generally indicates a liquid circulating intermediate circuit used to recover heat from exhaust air 3. Circuit 6 has a first heat exchanger 7 which transfers heat from a liquid, such as a mixture of water and glycol, to fresh supply air and a second heat exchanger 8 to transfer heat from exhaust air to liquid. The direction of liquid flow in the circuit 6 is indicated by the pump 9, 10 is a liquid expansion vessel. Arrow 11 indicates the air that is taken past the si-20 weather heat exchanger 7.

Numbers 12, 13, 14 and 15 denote supply line, bypass line, exhaust line and recirculation line, respectively, 16 and 17 are fans, 18 is a filter, and 19, 20, 21 and 22 are fresh supply air, bypass air, recirculated air and ventilation air. controls.

Temperature sensors located in the air-conditioned space are indicated by reference numerals 23, 24 and 25, their coordination unit is denoted 26. The unit 26, as well as the sensor 27 located behind the supply air fan 16, is connected 30 to a temperature CPU 29 which controls the controllers 20 depending on the received signals. and 21 the operation of the actuator 30 and the operation of the possible supply air preheater 31. The controls 19 and 22 can be manually operated and adjusted according to the need for breathing.

35 In warm weather, when heat recovery is not required, the air conditioning system may be switched off. When the outside air temperature is in the range of about + 5 ° C to about -5 ° C, whereby only part of the exhaust air heat is needed to maintain the desired indoor temperature, fresh supply air is partially introduced as bypass air via line 13. As the need for heat recovery increases, the bypass line 13 is closed and all the supply air 5 flows through the heat exchanger 7. If the outside air temperature continues to fall, the heat of the ventilation air 5 gradually becomes insufficient, after which the exhaust air 3 is added and the excess exhaust air is recirculated back via the line 15. With such recirculation, it is possible to keep the air conditioning system self-sufficient at an outdoor temperature as low as about -25 ° C, after which the preheater 31 is put into operation. Due to the high temperature of the exhaust air 3, the heat exchanger 8 is not susceptible to freezing but it is advisable to monitor the liquid temperature 15 in the line 32, e.g. by a sensor 33 adapted to influence the valve 34 to circulate the liquid at least partially in the circuit 9-32-32.

As has been shown above, what is central to the air-conditioning system according to the invention is that the ventilation is dimensioned in a so-called according to respiratory needs. This does not limit the ventilation to any certain minimum amount in which breathing air should somehow be tolerated in the cattle shelter or the like, but it is naturally intended that the cattle shelter 25 has first-class breathing air that does not interfere with residence or reduce livestock yield. Consequently, a certain oversizing of ventilation is within the scope of the invention, as the phrase "at least substantially on the basis of respiratory needs" has been shown. However, the amount of ventilation air is decisively lower than in previously known air-conditioning systems for livestock shelters or the like.

Claims (4)

6 73067 An air conditioning system for livestock shelters or the like, the system comprising means for recovering heat, characterized in that when the need for heat recovery occurs, the air temperature in the room is kept higher than the standard value, preferably so high that the exhaust air can absorb at least the humidity load of the room to be ventilated. substantially, the amount of ventilation being reduced to a level substantially determined by the need to remove gases harmful to respiration, in order to increase heat recovery and thus reduce energy consumption, and that in order to increase heat recovery , to utilize the energy bound to the air as water vapor in the condensation of moisture, and that this additional air is recycled back to said space mixed with fresh fresh air. An air conditioning system according to claim 1, comprising a liquid circulating intermediate circuit (6) with first heat exchangers (7) for fresh air heating and second heat exchangers (8) for cooling the exhaust air (3) and recovering heat therefrom, characterized in that the exhaust air temperature of the second heat exchanger is maintained. (8) after lower than the air-conditioned space without dew point. Air conditioning system according to Claim 1 or 2, characterized in that the heat exchanger (8) has at least substantially vertical channels as heat exchanger surfaces for recovering heat from the exhaust air, in order to keep the heat exchanger (8) clean by means of condensate flow. Air conditioning system according to any one of the preceding claims, characterized in that the air temperature in said space is maintained in the range of + 13 ° C to + 17 ° C.