Ventilation Unit For Refrigeration Plants

Abstract

A ventilation unit (1) designed for installation and use at a refrigeration plant has a fan and a heat exchanger (3) arranged in series with the fan. The fan is designed and positioned with regard to the heat exchanger (3) so as it delivers, in operation, an air volume flow through the heat exchanger (3) and out from the ventilation unit. The fan is designed as a diagonal fan (2). The diagonal fan axially draws in the air volume flow during operation and blows it out diagonally at an angle relative to its axis of rotation (RA).

Claims

1-13. (canceled)

14. A ventilation unit designed for installation and use at a refrigeration plant comprising: a fan and a heat exchanger arranged in series with the fan, the fan is designed and positioned with regard to the heat exchanger so as to deliver, in operation, an air volume flow through the heat exchanger and out from the ventilation unit; the fan is designed as a diagonal fan, the diagonal fan axially draws in the air volume flow during operation and blows it out diagonally at an angle relative to its axis of rotation (RA); and the heat exchanger is designed to cool the air volume flow down to a mean delivery temperature of 15 C. in order to form a cold air volume, and the cold air volume flow can be directly drawn in and blown out by the diagonal fan.

15. The ventilation unit as claimed in claim 14, wherein the diagonal fan is designed to draw in the air volume flow axially and to blow it out diagonally at an angle of 10-80, especially an angle of 25-60 with respect to its axis of rotation (RA).

16. The ventilation unit as claimed in claim 14, wherein the diagonal fan is designed and arranged in the ventilation unit to draw in the air volume flow axial through the heat exchanger and to blow it out from the ventilation unit into the free surroundings.

17. The ventilation unit as claimed in claim 14, wherein the heat exchanger for the diagonal fan generates, by progressive frosting during operation, a flow resistance increasing from a starting flow resistance with a first resistance characteristic (A) to a frosting resistance with a second resistance characteristic (B) and the diagonal fan is designed to have its highest efficiency range in an area of a third resistance characteristic (C) of the heat exchanger, wherein the third resistance characteristic (C) lies between the first and the second resistance characteristic (A, B), and the resistance characteristics (A, B, C) are characterized by an increasing backpressure psf [Pa] plotted against a delivered air quantity qv [m3/h].

18. The ventilation unit as claimed in claim 14, wherein the diagonal fan and the heat exchanger are joined together by a housing, the housing forms a closed flow duct for the air volume flow.

19. The ventilation unit as claimed in claim 14, wherein the ventilation unit is designed as an integrated structural unit for complete arrangement and fastening on the refrigeration plant.

20. The ventilation unit as claimed in claim 14, wherein the heat exchanger is designed as an evaporator.

21. The ventilation unit as claimed in claim 14, further comprising a guide device, the guide device is arranged in a blowout portion of the diagonal fan and designed to deflect the air volume flow blown out by the diagonal fan in a diagonal direction into an axial direction.

22. The ventilation unit as claimed in claim 21, wherein the guide device is designed as a single piece on the diagonal fan.

23. The ventilation unit as claimed in claim 20, wherein the guide device is designed to transform a spin of the air volume flow produced by the diagonal fan partly into static pressure.

24. The ventilation unit as claimed in claim 14, wherein the diagonal fan has a co-rotating cover disk.

25. The ventilation unit as claimed in claim 18, wherein the housing forms an air guidance for the air volume flow produced by the diagonal fan.

Description

DRAWINGS

[0024] FIG. 1 is a cross-section schematic view of a ventilation unit not pertaining to the disclosure with an axial fan of the prior art to illustrate the flow behavior in the frosted state;

[0025] FIG. 2 is a cross-section schematic view of the ventilation unit of FIG. 1 in a state without frosting;

[0026] FIG. 3 is a cross-section schematic view of a ventilation unit according to the disclosure in the frosted state; and

[0027] FIG. 4 is a diagram to show the design of the ventilation unit according to the disclosure.

DETAILED DESCRIPTION

[0028] FIG. 1 shows the basic schematic layout of the ventilation unit according to the disclosure, but with an axial fan 11 connected to a heat exchanger 10, in order to illustrate the fluidic problems. FIG. 1 shows a frosted state of the heat exchanger 10 and a resulting substantially radial outflow of the axial fan 11. A thermal short circuit is produced on the flow path 8 represented by arrows. Air is blown out from the axial fan 11 and returns once more to the intake zone of the heat exchanger. Furthermore, an inflow 9 occurs at the blowout side in the hub zone of the axial fan 11, on which the outflow is superimposed. In the frosted state of the heat exchanger, little or nothing remains of the actual purely axial outflow provided in the nonfrosted state, as shown for example in FIG. 2.

[0029] FIG. 3 shows schematically a ventilation unit 1 according to the disclosure in the frosted state with a diagonal fan 2 and a heat exchanger 3, designed as an evaporator, arranged in series with it. The heat exchanger 3 and the diagonal fan are joined together by a housing 5. The housing 5 forms a flow duct. Both the diagonal fan 2 and the heat exchanger 3 are installed and secured in the housing 5. Thus, the ventilation unit is an integrated structural unit. On the blowout portion of the diagonal ventilator 2, a protective grille is arranged. The ventilation unit 1 in its schematically represented form is designed for installation and use at a refrigeration plant.

[0030] In operation, the diagonal fan 2 draws in an air volume flow from the axial direction through the heat exchanger 3. The diagonal fans blows out the air despite frosting, from the ventilation unit 1 diagonally in an angle =30 with respect to the axis of rotation RA of the diagonal fan 2 into the open surroundings, such as a cold chamber. The diagonal outflow path 7 is indicated by arrows.

[0031] The heat exchanger 3 cools the air volume flow down to a mean delivery temperature equal to or less than 15 C., especially equal to or less than 5 C., in order to form the cold air volume flow, which is taken in directly by the diagonal fan 2.

[0032] The ventilation unit 1 according to the disclosure in FIG. 3 with the diagonal fan 2 may be interpreted, as compared to the embodiment with an axial fan 10 represented in FIG. 1, in the manner shown in FIG. 4 with the aid of a diagram of the delivered air volume qv [m3/h] plotted against the pressure psf [Pa]. The fan characteristics 11, 2 of the axial fan 11 of FIG. 1, the diagonal fan 2 of FIG. 3, as well as three resistance characteristic curves A, B, C due to different frosting states of the heat exchanger 3, are plotted in FIG. 4.

[0033] The flow resistance of the heat exchanger 3 increases during operation by progressive frosting from a starting flow resistance with a first resistance characteristic A for the diagonal fan to a frosting resistance with a second resistance characteristic B. In the state of the second resistance characteristic, a defrosting process is initiated for the heat exchanger 3. The diagonal fan 2, on the other hand, is designed such by its diagonal blowout direction that it has its highest efficiency range in a region of the third resistance characteristic C of the heat exchanger 3. The third resistance characteristic C lies between the first and second resistance characteristic A, B. The resistance characteristics A, B, C are characterized by an increasing backpressure psf [Pa] plotted against the delivered air volume qv [m3/h].

[0034] The ventilation unit 1 according to the disclosure with the diagonal fan 2 can be operated for a longer time and with higher efficiency in the region of the resistance characteristic C for the same corresponding delivery volume, as compared to a layout with the axial fan 11. The axial fan 11 only functions per design in the region of the resistance characteristic A. The absolute difference is indicated in the diagram by the fan characteristic curves 11, 2 of the axial fan 11 and diagonal fan 2.