WO2005075896A1

WO2005075896A1 - Method and apparatus for cooling ventilation air to be supplied to a space

Info

Publication number: WO2005075896A1
Application number: PCT/NL2005/000087
Authority: WO
Inventors: Abraham Anthony John De Graaff
Original assignee: J.E. Stork Ventilatoren B.V.
Priority date: 2004-02-06
Filing date: 2005-02-04
Publication date: 2005-08-18
Also published as: EP1711751A1

Abstract

The invention relates to a method for cooling outside air which is being supplied to a space, for instance a home, for ventilation thereof, wherein the supply air is brought into indirect heat-exchanging contact with discharge air extracted from the space. Ventilation and cooling of the space can thus be combined. The invention also relates to an apparatus for performing this method. Such a cooling apparatus is provided with means for bringing the supply air into indirect heat-exchanging contact with discharge air extracted from the space, for instance in the form of a compression refrigerating device with an evaporator which is connected to a duct for the supply of air and a condenser connected to a duct for discharge of air.

Description

METHOD AND APPARATUS FOR COOLING VENTILATION AIR TO BE SUPPLIED TO A SPACE

The invention relates to a method for cooling outside air which is being supplied to a space for ventilation thereof. In recent years the summers in regions with typically temperate climates have become increasingly warmer. This results in a need for cooling, particularly in buildings such as offices and homes. Large-scale use is made of air- conditioners to cool offices. The conditioning of air is however an expensive process requiring much energy. This is usually still too expensive for use in homes. There therefore exists a need for a method with which cool air can be supplied to buildings, in particular homes, in simple manner and at relatively low cost. This is achieved according to the invention in a method as described above in that the supply air is brought into indirect heat-exchanging contact with discharge air extracted from the space. By making use of air already being used for ventilation in order to cool the space, an effective cooling can be obtained with only a little extra effort. By causing this cooling to take place indirectly a greater degree of cooling of the supply sir can moreover be achieved than would be possible in the case of direct contact. Both the supply air and the discharge air are preferably brought into heat-exchanging contact with an intermediate medium, which is evaporated by the supply air and condensed by the discharge air. In the manner of a compression refrigerating device the discharge air is further heated and the supply air cooled more deeply by this intermediate medium than would be possible on the basis of their temperature difference with direct heat-exchanging contact . In order to enable a greater amount of energy to be extracted from the intermediate medium during the condensation, and so to enable the supply air to be cooled more deeply during evaporation of the intermediate medium, a part of the supply air is preferably admixed directly to the discharge air before the discharge air is brought into contact with the intermediate medium. A greater airflow over the condenser is thus obtained. In order to optimize cooling, and minimize the associated energy consumption, the supply air and the discharge air can be placed in direct heat-exchanging contact with each other before the indirect heat-exchanging contact. The supply air is hereby precooled to some extent, whereby a higher cooling capacity is achieved with the same energy consumption. From the viewpoint of installation it is recommended here that condensation formed during the indirect heat-exchanging contact and condensation formed during the direct heat-exchanging contact are collected and discharged together. According to a preferably applied variant of the method, the temperature of the supply air is adjusted by varying the amount of outside air supplied to the space per unit of time. With a constant cooling capacity the temperature of the ventilation air can thus be decreased by decreasing the flow rate. The invention further relates to an apparatus for cooling outside air being supplied to a space for ventilation thereof, with which the above described method can be performed. According to the invention such a cooling apparatus is characterized by means for bringing the supply air into indirect heat-exchanging contact with discharge air extracted from the space . For the reasons set forth above, the indirect contact means preferably comprise at least one compression refrigerating device with an evaporator which is connected to a duct for the supply of air and a condenser connected to a duct for discharge of air. The cooling apparatus can advantageously be provided here with means for diverting a part of the supply air directly to the condenser. In order to enable a part of the supply air to be fed in efficient manner to the condenser, and to avoid direct contact between the supply air and the discharge air, the diverting means preferably comprise a fan and a non-return valve co-acting therewith. As indicated above, it is recommended that the cooling apparatus is provided with a lαeat exchanger connected before the compression refrigerating device and connected to the air inlet and the air outlet. A structurally simple and compact embodiment of the cooling apparatus is obtained when the compression refrigerating device and the heat exchanger are combined. The compression refrigerating device can thus be readily combined with a heat exchanger or heat recovery installation already present in a home, such as made commercially available in different forms by applicant. The compression refrigerating device and the heat exchanger can then advantageously have joint provisions here for draining condensation formed therein. When the cooling apparatus is provided with at least one fan for urging supply air to the space, or extracting discharge air therefrom, this at least one fan is preferably connected controllably to means for detecting the temperature of the supply air. When these detecting means, for instance temperature sensors, determine that the supply air is too warm, the airflow can be reduced by adjusting down the at least one fan, and the degree of cooling thereof can thus be increased while the cooling capacity remains constant. The invention will now be elucidated on the basis of an embodiment and with reference to the accompanying drawing, in which: Fig. 1 shows a schematic diagram of the method for cooling ventilation air according to the invention, Fig. 2 is a perspective view of a combination of a compression refrigerating device and a heat exchanger of a ventilation system, and Fig. 3 is a partly cut-away, perspective top view of the combination apparatus of fig. 2. To perform the method according to the invention use is made of a cooling apparatus 1 in combination with a ventilation system 11. Ventilation system 11 serves in known manner to draw in fresh outside air A by means of a fan 12 via a suction duct 13, and to supply this air via a feed duct 14 as ventilation air V to one or more spaces S. In addition, ventilation system 11 draws air R out of space (s) S via a return duct 16 using a fan 15 and guides it via a discharge duct 17 back to the environment as discharge air D. Ventilation system 11 is further provided in known manner with a heat exchanger 10, in which the used air drawn from space (s) S is brought into heat-exchanging contact with the fresh outside air to be used for ventilation. This heat exchanger 10 is particularly important in the winter to transfer the heat present in the discharge air to the cold outside air, so that this latter is already preheated and heat loss resulting from the ventilation is prevented as far as possible. In the summer, when outside air A will generally be warmer than the air in the space (s) S to be ventilated, the ventilation air is already cooled to some extent in this heat exchanger 10. This cooling is however often insufficient to ensure a pleasant indoor climate. According to the invention the air to be supplied to space (s) S is therefore cooled still further. To this end this air is brought into indirect heat- exchanging contact in a compression refrigerating device 2 with the air which is being discharged to the environment. The compression refrigerating device 2 comprises an evaporator 3 and a condenser 4 which are mutually connected by a conduit 9 in which a coolant circulates. This coolant, which functions as intermediate medium for the indirect heat- exchanging contact between the supply air and the discharge air, is pumped round in conduit 9 by a compressor 18 which once again brings the vaporous coolant from evaporator 3 to a pressure such that it can condense in condenser 4. A pressure-reducing element 19 is further arranged between condenser 4 and evaporator 3, whereby the condensed coolant once again expands and is reduced so much in pressure that it can evaporate in evaporator 3. In the shown embodiment a choice has been made for an expansion valve, although a capillary could be applied instead. The fresh air to be supplied to space (s) S is guided from heat exchanger 10 via feed duct 14 to evaporator 3, where the heat required to evaporate the coolant is extracted from the air. The used air coming from space (s) S is simultaneously guided from heat exchanger 10 via discharge duct 17 to condenser 4, where this discharge air is heated so that the coolant cools and condenses. An additional quantity of air can be guided through condenser 4 in order to enhance the condensation. Provided for this purpose is a branch duct 8 through which a part of the indrawn outside air A can be guided directly to condenser 4. Arranged in this branch duct 8 is a small auxiliary fan 6 which draws in the outside air A. An automatic return valve 7 is also accommodated in branch duct 8. This is open as long as fan 6 is in operation, but remains closed in all other cases, so that no air can flow out of discharge duct 17 to suction duct 13. Contact is thus avoided between the - generally contaminated - discharge air and the fresh outside air. Fans 12 and 15 can further be controllably connected to means (not shown here) for detecting the temperature of the ventilation air V being supplied to the space (s). By controlling the fans 12, 15, and thereby the flow rate of ventilation air V, the temperature thereof can be adjusted without the operation of cooling apparatus 1 having to be controlled. The structural embodiment of cooling apparatus 1 is shown in fig. 2 and 3. Here is shown that it is combined with heat exchanger 10, which nowadays often forms part of the ventilation system 11 usually already present in homes. Cooling apparatus 1 comprises a housing 20 which can be mounted on a housing 21 of heat exchanger 10 and which has in its bottom 22 four openings 23 (of which only two are shown here) which correspond with the supply and discharge ducts 13, 14, 16, 17 of heat exchanger 10. Housing 20 is divided by separating walls 24, 25, 26,

27 into five compartments. Compressor 18 and expansion valve 19 (not shown) are placed in a central compartment, while evaporator 3 and condenser 4 are accommodated in two diametrically opposite compartments. The two remaining compartments function only as respective components of suction duct 13 and return duct 16. The auxiliary fan 6 is also accommodated in the compartment forming part of suction duct 13. Two further compartments are also formed by inclining walls 28, 29 for the purpose of receiving all manner of accessories, such as control electronics and the like. On the top the housing 20 is closed by a cover 30 in which four openings are formed for connection to supply and discharge ducts (not shown here) of ventilation system 11. There is the chance during use of cooling apparatus 1 of condensation forming at the position of evaporator 3 as a result of the low temperatures prevailing there. Provisions are therefore made to collect and drain this condensation. In the shown embodiment the heat exchanger 10 is already provided with a condensation drain, and cooling apparatus 1 is connected to heat exchanger 10 such that condensation created in cooling apparatus 1 also runs into the condensation drain of heat exchanger 12 and is discharged. The above described apparatus thus provides the option of combining the ventilation of a building, in particular a home, with the cooling thereof in efficient manner and using relatively simple means. The invention is expressly not limited to the above exemplary embodiment. All new aspects of the described method and apparatus can be used per se in other combinations while retaining the associated advantages. The scope of the invention is defined solely by the following claims.

Claims

1. Method for cooling outside air (A) which is being supplied to a space (5) for ventilation thereof, characterized in that the supply air (A) is brought into indirect heat-exchanging contact with discharge air (R) extracted from the space (S) .

2. Method as claimed in claim 1, characterized in that both the supply air (A) and the discharge air (R) are brought into heat-exchanging contact with an intermediate medium, which is evaporated by the supply air (A) and condensed by the discharge air (R) .

3. Method as claimed in claim 1 or 2, characterized in that a part of the supply air (A) is directly admixed to the discharge air (R) before the discharge air (R) is brought into contact with the intermediate medium.

4. Method as claimed in any of the foregoing claims, characterized in that the supply air (A) and the discharge air (R) are placed in direct heat-exchanging contact with each other before the indirect heat-exchanging contact.

5. Method as claimed in claim 4, characterized in that condensation formed during the indirect heat-exchanging contact and condensation formed during the direct heat- exchanging contact are collected and discharged together.

6. Method as claimed in any of the foregoing claims, characterized in that the temperature of the supply air is adjusted by varying the amount of outside air (A) supplied to the space (S) per unit of time.

7. Apparatus (1) for cooling outside air (A) being supplied to a space (S) for ventilation thereof, characterized by means (2) for bringing the supply air (A) into indirect heat-exchanging contact with discharge air (R) extracted from the space (S) .

8. Cooling apparatus (1) as claimed in claim 7, characterized in that the indirect contact means (2) comprise at least one compression refrigerating device with an evaporator (3) which is connected to a duct (14) for the supply of air and a condenser (4) connected to a duct (17) for discharge of air.

9. Cooling apparatus (1) as claimed in claim 8, characterized by means (5) for diverting a part of the supply air (A) directly to the condenser (4).

10. Cooling apparatus (1) as claimed in claim 9, characterized in that the diverting means (5) comprise a fan (6) and a non-return valve (7) co-acting therewith.

11. Cooling apparatus (1) as claimed in any of the claims 8-10, characterized by a heat exchanger (10) connected before the compression refrigerating device (2) and connected to the air inlet and the air outlet.

12. Cooling apparatus (1) as claimed in claim 11, characterized in that the compression refrigerating device

(2) and the heat exchanger (10) are combined.

13. Cooling apparatus (1) as claimed in claim 11 or

12, characterized in that the compression refrigerating device (2) and the heat exchanger (10) have joint provisions for draining condensation formed therein.

14. Cooling apparatus (1) as claimed in any of the claims 7-13, characterized by at least one fan (12, 15) for urging supply air (A) to the space (S) and/or extracting discharge air (R) therefrom, which at least one fan (12, 15) is connected controllably to means for detecting the temperature of the supply air (A) .