A GREENHOUSE HAVING A CLIMATE CONTROL SYSTEM, CLIMATE CONTROL SYSTEM AND METHOD OF OPERATING THE GREENHOUSE

Abstract

A greenhouse for growing plants includes a growing area for growing crops and a climate control system for controlling the greenhouse interior climate in the growing area. This control system includes a condenser for dehumidifying greenhouse air, a greenhouse air heat exchanger for heat-exchange between greenhouse air derived from the growing area upstream of the air inlet of the condenser and in the condenser dehumidified greenhouse air downstream of the air outlet of the condenser, a first controllable bypass for allowing greenhouse air to bypass the greenhouse air heat exchanger, a controllable fan, a mixing chamber in fluid communication with the air discharge of the heat exchanger and with the growing area and having a controllable inlet for introducing ambient air from the greenhouse exterior environment, and an outlet having a controlled fan for air in fluid communication with the growing area.

Claims

1. A greenhouse for growing plants, comprising: a growing area for growing crops, a climate control system for controlling the greenhouse interior climate in the growing area, wherein the climate control system comprises: a condenser for dehumidifying greenhouse air having, at the air side, an air inlet for supplying greenhouse air and an air outlet for discharging dehumidified air, and, at the liquid side, a liquid inlet for supplying an aqueous liquid flow and a liquid outlet for discharging an in the condenser heat exchanged aqueous liquid flow; and a greenhouse air heat exchanger for heat-exchange between greenhouse air derived from the growing area upstream of the air inlet of the condenser and in the condenser dehumidified greenhouse air downstream of the air outlet of the condenser, comprising an air inlet of greenhouse air from the greenhouse interior climate, wherein the air inlet is connected to the air inlet of the condenser through the greenhouse air heat exchanger, and an air discharge of heat exchanged, dehumidified greenhouse air, wherein the air outlet of the condenser is connected to the air discharge through the greenhouse air heat exchanger, a first controllable bypass for allowing greenhouse air to bypass the greenhouse air heat exchanger, a controllable fan configured to generate a flow of greenhouse air through the greenhouse air heat exchanger and the condenser, a mixing chamber in fluid communication with the air discharge of the greenhouse air heat exchanger and in fluid communication with the growing area for introducing greenhouse air and having a controllable inlet for introducing ambient air from the greenhouse exterior environment, and an outlet for air in fluid communication with the growing area; and a controlled fan in the outlet for generating a flow of air from the mixing chamber to the greenhouse growing area.

2. The greenhouse according to claim 1, wherein the first controllable bypass is fluidly connected to the air inlet of the condenser.

3. The greenhouse according to claim 1, wherein the first controllable bypass is provided between the air outlet of the condenser and the air discharge of the greenhouse air heat exchanger.

4. The greenhouse according to claim 1, wherein the air discharge of the greenhouse air heat exchanger is connected to an air distributor, positioned in the mixing chamber, for distributing the heat exchanged, dehumidified greenhouse air in the mixing chamber.

5. The greenhouse according to claim 4, wherein the air inlet of the greenhouse air heat exchanger is positioned at a position higher than the controllable inlet for introducing ambient air, preferably the air inlet is positioned at a position higher than air distributor.

6. The greenhouse according to claim 1, wherein the outlet for air in fluid communication with the growing area is positioned below the air inlet of the greenhouse air heat exchanger.

7. The greenhouse according to claim 1, wherein the condenser and greenhouse air heat exchanger are positioned inside the mixing chamber, the mixing chamber preferably being a working and maintenance space (so called “corridor”) of the greenhouse.

8. The greenhouse according to any one of the preceding claims 1-6, wherein the condenser and greenhouse air heat exchanger are positioned outside the mixing chamber, the mixing chamber preferably being arranged at a head wall of the greenhouse, more preferably between head supporting posts.

9. The greenhouse according to claim 1, further comprising a heat pump configured for cooling the aqueous liquid flow that has been heat exchanged in the condenser, preferably to the freezing point of water or lower, having a heat pump inlet for entering the aqueous liquid flow that has been used for heat exchange in the condenser, and a heat pump outlet for discharging the cooled aqueous liquid flow, wherein the heat pump inlet is connected to the liquid outlet of the condenser and the heat pump outlet is connected to the liquid inlet of the condenser.

10. The greenhouse according to claim 9, further comprising a storage for temporarily storing the cooled aqueous liquid flow and ice having a storage inlet for supplying the liquid flow from the heat pump, which storage inlet is connected to the heat pump outlet via an intermediate conduit and a storage outlet for discharging an aqueous liquid flow, which storage outlet is connected to the liquid inlet of the condenser via the aqueous cooling liquid supply conduit.

11. The greenhouse according to claim 1, wherein the growing area comprises a plurality of growing sections, wherein each growing section is connected to at least one climate control system.

12. The greenhouse according to claim 11, wherein the condensers of the climate control systems are connected to a single heat pump according to claim 8.

13. The greenhouse according to claim 1, wherein the controllable fan is arranged upstream of the greenhouse air heat exchanger, and the controllable bypass is connected at one end to the air inlet of the greenhouse air heat exchanger and at the other end to the air inlet of the condenser.

14. A method of operating the greenhouse according to claim 1, wherein if the condensation capacity of the condensers is sufficient to maintain the greenhouse interior climate at a predetermined level of temperature, humidity and carbon dioxide, the greenhouse is operated in a closed condition without introduction of ambient air through the inlet of ambient air into the mixing chamber, and if the condensation capacity of the condensers is insufficient to maintain the greenhouse interior climate at a predetermined level of temperature, humidity and carbon dioxide, the greenhouse is operated in a semi-closed condition with introduction of ambient air through the inlet of ambient air into the mixing chamber.

15. A climate control system for controlling the greenhouse interior climate in the growing area, comprising: a condenser for dehumidifying greenhouse air having, at the air side, an air inlet for supplying greenhouse air and an air outlet for discharging dehumidified air, and, at the liquid side, a liquid inlet for supplying an aqueous liquid flow and a liquid outlet for discharging an in the condenser heat exchanged aqueous liquid flow; and a greenhouse air heat exchanger for heat-exchange between greenhouse air derived from the growing area upstream of the air inlet of the condenser and in the condenser dehumidified greenhouse air downstream of the air outlet of the condenser, comprising an air inlet of greenhouse air from the greenhouse interior climate, wherein the air inlet is connected to the air inlet of the condenser through the greenhouse air heat exchanger, and an air discharge of heat exchanged, dehumidified greenhouse air, wherein the air outlet of the condenser is connected to the air discharge through the greenhouse air heat exchanger, a first controllable bypass for allowing greenhouse air to bypass the greenhouse air heat exchanger, a controllable fan configured to generate a flow of greenhouse air through the greenhouse air heat exchanger and the condenser, a mixing chamber in fluid communication with the air discharge of the greenhouse air heat exchanger and in fluid communication with the growing area for introducing greenhouse air and having a controllable inlet for introducing ambient air from the greenhouse exterior environment, and an outlet for air in fluid communication with the growing area; and a controlled fan in the outlet for generating a flow of air from the mixing chamber to the greenhouse growing area.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The invention is illustrated in the attached drawings, wherein:

[0049] FIG. 1 is a schematic representation in side view of an embodiment of a greenhouse provided with a climate control system according to the invention;

[0050] FIG. 2 is another side view of the embodiment of a greenhouse of FIG. 1;

[0051] FIG. 3 is a top view of the embodiment of a greenhouse of FIG. 1;

[0052] FIG. 4 shows a schematic representation in side view of another embodiment of a greenhouse provided with a climate control system according to the invention;

[0053] FIG. 5 is another side view of the embodiment of a greenhouse of FIG. 4;

[0054] FIG. 6 is a top view of the embodiment of a greenhouse of FIG. 4;

[0055] FIG. 7 shows an embodiment of a cold water supply system to the condenser of the climate control system of the greenhouse according to the invention;

[0056] FIG. 8 shows another embodiment of a greenhouse according to the invention; and

[0057] FIGS. 9-11 show various embodiments of the bypass over the greenhouse air heat exchanger.

DETAILED DESCRIPTION OF THE INVENTION

[0058] In the various Figures the same parts are indicated by the same reference numerals.

[0059] FIG. 1-3 show an embodiment of a greenhouse for growing plants, culturing flowers, fruits and/or vegetables including a climate control system according to the invention. A greenhouse is indicated in its entirety by reference numeral 10 and its periphery is represented by dotted lines. The greenhouse 10 comprises a growing area 12 and a working and maintenance space (“corridor”) 14. The growing area 10 comprises a plurality of culturing sections, each with its own gutter and associated perforated hose (schematically shown as a rectangle 16 in FIG. 3 with its dedicated fan 17). The space 14 having the function of mixing chamber is separated from the growing area 12 by a separation wall 19 and further delimited by bottom 18, roof 20 and upstanding adjacent glass panel side wall 22 and glass panel head walls 24 and 26. The space 14 essentially extends along the entire side wall 22. The separation wall 16 is provided with a hinged flap 28 at the top covering an inlet opening 30 from the growing area 12 to the space 14. In the space 14 a greenhouse heat exchanger 32 is arranged. The heat exchanger 32 has an air inlet 34 for entering greenhouse air from the space 14, preferably arranged near the opening 30. If required, a feed conduit 36 extending from the vicinity of the opening 30 to the air inlet 34 may be provided as shown. The heat exchanger 32 also has an air outlet 38, e.g. a conduit, provided with a control valve 40 and first bypass 42 having control valve 44. The air outlet 38 is connected to the inlet 46 of condenser 48, wherein greenhouse air derived from the heat exchanger 32 and optionally bypass 42 is dehumidified by cooling with cold water, flowing from supply conduit 50 in counter current arrangement through the condenser 48 to return conduit 52. The dehumidified air flows from the condenser 48 via outlet 54 back to the heat exchanger 32 where the dehumidified air is heated by the incoming greenhouse air. An additional controllable first bypass 55 having control valve 57 is provided between the air outlet 54 of the condenser 48 and air discharge 58 of the heat exchanger 32. In this embodiment fan 56 in the air discharge 58 of heat exchanger 32 draws the greenhouse air through the assembly of heat exchanger 32 and condenser 48 and feeds the heat exchanged dehumidified air to air distributor 60. At a height below the air distributor 60 an inlet conduit 62 provided with control valve 64 for introducing air from the environment into the space 14 is arranged in the side wall 22. If control valve 64 is opened, the fresh air and heat-exchanged dehumidified air, and any recycling greenhouse air that bypasses both the condenser 48 and heat exchanger 32, are mixed and forced to flow by fan 17 through the outlet 65 to the growing area 12 via the respective hose 16. As is apparent in the space 14 a number of assemblies of condensers 48 and associated heat exchangers 30 and air distributors 60 are arranged, each assembly serving a plurality of fans 17 and hoses 16. A controller 100 adjusts the various flows through the control valves, preferably based on measurements, e.g. sensors, of humidity, temperature and carbon dioxide level.

[0060] FIG. 4-6 show another embodiment of a greenhouse provided with a climate control system according to the invention. In this embodiment the assemblies of heat exchanger 32 and condenser 48 are arranged above mixing chambers 14, each between supports 66 at the head wall 24. The air distributors 60 are positioned within the mixing chamber 14. The mixing chamber 14 is provided with a greenhouse air inlet 68.

[0061] Condensed water is collected from the condenser 48 at 69. This water can be reused for watering the crops grown in the growing area 12.

[0062] FIG. 7 shows an embodiment of a cold water supply to the local condensers 48 from a central heat pump system 70 arranged for cooling down an aqueous liquid flow from the condenser 48 via return conduit 52, and a storage 72 for keeping a volume of aqueous liquid and ice connected to the condenser via supply conduit 50.

[0063] In particular, at the liquid side (cold side) the condenser 48 is connected to the supply conduit 50 for supplying a flow of an aqueous liquid, typically water, e.g. having a temperature of less than 6° C., preferably 1° C. or less, and to the return conduit 52 for discharging the heat exchanged aqueous liquid, e.g. having a temperature of about 5-15° C. The flow of aqueous liquid is from the storage 72 where it leaves having a temperature of about 0° C. The supply conduit 50 is provided with a supply pump 74. The flow of aqueous liquid exiting the condenser 48 is discharged via return conduit 52 to the heat pump 70, and the mixture of ice and water or cooled mixture of water and freezing agent obtained therein is transferred to storage 72 via intermediate aqueous cooling liquid channel section 76. A loop section 78 may be provided between return conduit 52 and supply conduit 50 allowing—by means of control valve 80 and circulation pump 82—to circulate the aqueous water flow over the condenser 48. Likewise the aqueous liquid flow may be circulated over the heat pump 70 and storage 72 bypassing condenser 48 via a bypass section 84 arranged between the supply conduit 50 and return conduit 52 provided with a bypass valve 86. The heat pump system 70 transfers heat extracted at its heat extraction side from the aqueous liquid flow in the aqueous cooling liquid circuit to its heat release side into the general heating system 90 of the greenhouse, such as a tube rail system providing both a heating function and a conveyor function. A cooler 92, e.g. an air-cooled heat exchanger may be provided to cool the heating medium flowing in the heating system 90 by means of heating medium circulation pump 94, in particular between supply line 90a and return line 90b.

[0064] FIG. 8 shows another embodiment of a greenhouse according to the invention, wherein the controllable fan 56 is arranged in the feed conduit 36 to the greenhouse air heat exchanger 32. The bypass 42 over the exchanger 32 is connected with one of its ends to the conduit 36 downstream of the fan 56. The other end having a control valve 44 controlled by controller 100 is connected to the connecting duct that extends between the outlet 38 of the heat exchanger 32 and the inlet 46 of the condenser 48. Optionally an additional controllable bypass 55 having control valve 57 is arranged between the air outlet 54 of the condenser 48 and air discharge 58 of the heat exchanger 32. The fan 56 draws in greenhouse air and forces it through the greenhouse air heat exchanger 32 and the controlled bypass 42. Then the combined flow is subjected to condensation in condenser 48. The air flow resulting from condensation is reheated in the heat exchanger 32 against the incoming greenhouse air. Optionally a partial air flow downstream of the condenser 48 is allowed to bypass the heat exchanger 32 through bypass 55.

[0065] FIG. 9 shows another embodiment of a bypass 55 over the greenhouse air heat exchanger 32. This embodiment is mainly similar to the one of FIG. 1, except that at the feed side of the heat exchanger 32 and condenser 48 the first bypass 42 and control valves 44 and 40 are absent.

[0066] FIG. 10 shows yet another embodiment of a bypass 55 over the greenhouse air heat exchanger 32 downstream of the condenser 48. In this embodiment a partial flow of dehumidified air from the condenser 48 is passed via control valve 57 and bypass 55 directly into the mixing chamber, preferably to the inlet of ambient air (not shown). In this embodiment the fan 56 is arranged in the feed conduit 36.

[0067] FIG. 11 illustrates still another embodiment of a bypass 55 over the greenhouse air heat exchanger 32 downstream of the condenser 48, which embodiment is similar to that of FIG. 9, except that the fan 56 is arranged in the feed conduit 36.