IMPROVED AIR CONDITIONING SYSTEM

Abstract

There is presented a heating, ventilation and air conditioning (HVAC) system for conditioning air within a chamber, the system comprising: an inlet, an outlet, and a conditioning unit, the conditioning unit comprising a fan, and a heat exchanger configured to exchange heat with the air within the conditioning unit, wherein during operation, air is urged through conditioning unit by the fan such that heat is exchanged between the air and the heat exchanger, wherein the fan is configured to vary the flow rate of air urged through the conditioning unit to thereby control the amount of heat transferred between the air and the heat exchanger.

Claims

1. A heating, ventilation and air conditioning (HVAC) system for conditioning air within a chamber, the system comprising: an inlet, an outlet, and a conditioning unit, the conditioning unit comprising a fan configured to urge air into the system from the chamber via the inlet and out of the system into the chamber via the outlet, and a heat exchanger configured to exchange heat with the air within the conditioning unit, wherein during operation, air is urged through conditioning unit by the fan such that heat is exchanged between the air and the heat exchanger, wherein the fan is configured to vary the flow rate of air urged through the conditioning unit to thereby control the amount of heat transferred between the air and the heat exchanger.

2. The HVAC system according to claim 1, wherein the heat exchanger is configured such that the temperature of the heat exchanger is adjustable or the heat exchanger is configured such that the temperature of the surface of the heat exchanger is adjustable.

3. The HVAC system according to claim 2, wherein the HVAC system is configured to reduce the humidity of the air passing through the conditioning unit by adjusting the temperature of the heat exchanger below the dew point of the air.

4. The HVAC system according to claim 1, wherein the heat exchanger is a cooling coil.

5. The HVAC system according to claim 1, wherein the heat exchanger contains a coolant that flows through the heat exchanger.

6. The HVAC system according to claim 2, wherein the temperature of the heat exchanger is controlled by varying the coolant temperature.

7. The HVAC system according to claim 5, wherein the temperature of the heat exchanger is controlled by varying the flow rate of coolant through the heat exchanger.

8. The HVAC system according to claim 1, wherein the conditioning unit further comprises a controller, one or more sensors adjacent to the inlet, and one or more sensors adjacent to the outlet, and during use the controller is configured to (i) receive signals from the one or more sensors adjacent to the inlet and the one or more sensors adjacent to the outlet, (ii) determine whether the air entering the inlet is at a target temperature, and/or a target humidity and (iii) adjust the fan speed such that the air contacts the heat exchanger to transfer heat between the heat exchanger and the air to thereby reach the target temperature and/or humidity.

9. The HVAC system according to claim 2, wherein the conditioning unit further comprises a controller, one or more sensors adjacent to the inlet, and one or more sensors adjacent to the outlet, and during use the controller is configured to (i) receive signals from the one or more sensors adjacent to the inlet and the one or more sensors adjacent to the outlet, (ii) determine whether the air entering the inlet is at the target temperature, and/or the target humidity, (iii) adjust the fan speed such that the air contacts the heat exchanger to transfer heat between the heat exchanger and the air to thereby reach the target temperature, and (iv) adjusts the temperature of the heat exchanger to thereby reach the target humidity.

10. The HVAC system according to claim 1 further comprising a vent.

11. The HVAC system according to claim 1 further comprising an external inlet.

12. An enclosed space comprising the HVAC system according to claim 1.

13. The enclosed space according to claim 12, wherein the enclosed space is selected from the group a greenhouse, a vertical growth tower, an office space, a retail space, an industrial space, a commercial space, or a domestic space.

14. A method of conditioning air within a closed space using the HVAC system of claim 1, the method comprising the steps: (a) providing a HVAC system comprising an inlet, an outlet, and a conditioning unit, the conditioning unit comprising a fan configured to urge air into the system from the chamber via the inlet and out of the system into the chamber via the outlet, and a heat exchanger configured to exchange heat with the air within the conditioning unit, a controller, a first plurality of sensors adjacent to the inlet of the HVAC system; (b) setting one or more target values selected from the group humidity and temperature; (c) the controller receiving one or more readings from the first plurality of sensors and determining system values selected from the group humidity and temperature; (d) the controller comparing the system values with the target values and determining the difference between the target values and the system values; (e) the controller adjusting the fan speed and/or the temperature of the heat exchanger to adjust the heat exchanged between air in the conditioning unit and the heat exchanger and/or to adjust the humidity of the air; (f) repeating steps (c) to (e) until the system values are equal to the target values, or until the system values are within a predetermined range of values around the target values.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0053] Embodiments of the present invention will now be described, by way of non-limiting example, with reference to the accompanying drawings.

[0054] FIG. 1: A plan view of a HVAC system according to an embodiment;

[0055] FIG. 2: A side plan view of a vertical growth tower including a HVAC system according to an embodiment;

[0056] FIG. 3: A plan view of a HVAC system according to an embodiment;

[0057] FIG. 4: A side plan view of a vertical growth tower including a HVAC system according to an embodiment;

[0058] FIG. 5: A plan view of a HVAC system according to an embodiment;

[0059] FIG. 6: An example algorithm for controlling the temperature in a vertical growth tower comprising a HVAC system according to an embodiment; the dashed line indicates waiting for a predetermined period before performing the action; subroutines that run at all times, (1) fan control—speed control on the fan to maintain sensor 3 (S3)−sensor 4 (S4)=delivery pressure setpoint (2) maintain valve opening offsets to each other (e.g. valve 2 always 10% more open than valve 1);

[0060] FIG. 7: A schematic view of a positive pressure unit;

[0061] FIG. 8: A side plan view of a commercial space including a HVAC system according to an embodiment; and

[0062] FIG. 9: An example algorithm for controlling the temperature in a commercial space comprising a HVAC system according to an embodiment.

DETAILED DESCRIPTION

[0063] While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention and do not delimit the scope of the invention.

[0064] To facilitate the understanding of this invention, a number of terms are defined below. Terms defined herein have meanings as commonly understood by a person of ordinary skill in the areas relevant to the present invention. Terms such as “a”, “an” and “the” are not intended to refer to only a singular entity, but include the general class of which a specific example may be used for illustration. The terminology herein is used to describe specific embodiments of the invention, but their usage does not delimit the invention, except as outlined in the claims.

EXAMPLE 1

[0065] With reference to FIGS. 1 and 2 there is provided a vertical growth tower 1 comprising an array 2 of growth trays 4 arranged in a stack. Each growth tray 4 in the array 2 of growth trays has an array of LEDs (not shown) positioned on the underside of the growth tray 4 to provide light to the growth tray below it in the array. Adjacent to the array 2 of growth trays is a first conduit 6 from an HVAC system 8 having an outlet 10 associated with each growth tray 4 directing conditioned air to that growth tray. Each outlet 10 in the conduit comprises a valve 12 to control the flow of air out of the first conduit 6 to the associated growth tray. Adjacent to the array 2 of growth trays is a second conduit 14 to the HVAC system 8 having an inlet 16 associated with each growth tray 4 drawing air from that growth tray.

[0066] The HVAC system 8 comprises an inlet 18, an outlet 20, a controller 22, an external intake valve 24, an external vent 26 and a conditioning unit 28. The inlet 18 is connected to the second conduit 14 and the outlet 20 is connected to the first conduit 6. The conditioning unit 28 comprise a variable speed fan 30, a cooling coil 32 (acting as a heat exchanger), a coolant reservoir 34 containing water (acting as a coolant), a coolant heating/cooling unit 36 and a coolant pump 38. During use, air is drawn into the conditioning unit 28 via the inlet 18 by the variable speed fan 30, contacts the cooling coil 32 and passes out of the conditioning unit 28 via the outlet 20. Coolant is pumped through the cooling coil 32 by the coolant pump 38 in a circuit from the coolant reservoir 34 to the cooling coil 32 and back again.

[0067] The inlet 18 comprises a temperature sensor 40a, a humidity sensor 40b and a pressure sensor 40c, and the outlet 20 comprises a temperature sensor 42a, a humidity sensor 42b and a pressure sensor 42c. The controller 22 of the HVAC system 8 receives signals from the sensors of the inlet (40a, 40b, 40c) and the outlet (42a, 42b, 42c) of the HVAC system 8.

[0068] During use, the vertical growth tower 1 generates heat from the arrays of LEDs, and from the plants growing in the growth trays themselves. In addition, the plants growing in the trays transpire, thereby raising the humidity of the air in each tray.

[0069] Therefore, the HVAC system 8 is typically required to reduce the humidity of the air and to cool the air passing through the conditioning unit 28 of the HVAC system 8.

[0070] Accordingly, a target temperature, a target humidity and a target pressure are set for the vertical growth tower. The dew point for the air passing entering the inlet is determined by the controller 22 from the measured relative humidity and temperature recorded by the temperature sensor 40a and humidity sensor 40b at the inlet 18. During normal operation, the temperature of air entering the inlet 18 is higher than the target temperature for the tower 1, and therefore, the fan 30 urges the air through the conditioning unit 28 to contact the cooling coil 32 to thereby reduce the temperature of the air to the target temperature. The humidity of the air entering the inlet 18 is also often higher than the target humidity, and therefore the temperature of the cooling coil 32 is set to be below the determined dew point for the air entering the inlet 18 such that water condenses out of the air upon contact with the surface of the cooling coil 32 to thereby reduce the humidity of that air.

[0071] However, if the air entering the inlet 18 has a humidity that is approximately equal to the target humidity, the cooling coil temperature is maintained above the determined dew point for the air such that substantially no condensation occurs, and therefore the humidity level of the conditioned air is thereby maintained.

[0072] Accordingly, unlike conventional HVAC systems where the cooling coil has a fixed temperature, the air is not cooled, dehumidified, rehumidified and reheated to attain the target temperature and humidity, and therefore, the HVAC system of this example is more efficient than conventional HVAC systems.

[0073] Typically, the HVAC system maintains the temperature within the vertical growth tower within the range 23° C. to 32° C. The HVAC system maintains the humidity within the vertical growth tower within the range 50% to 80% relative humidity. The HVAC system maintains the pressure within the vertical growth tower to be approximately 10 Pa above ambient pressure.

[0074] If the pressure at the inlet 18 is determined to be less than the target pressure range, the external intake valve 24 is opened to draw additional air into the HVAC system to increase the pressure until the target pressure is reached.

[0075] In an alternative embodiment with reference to FIG. 4, the vertical growth tower 130 comprises an array of inlets 140 and an array of outlets 146 that comprise fewer outlets respectively than the number of growth trays 134 in the array of growth trays 132. Accordingly, a given inlet within the array of inlets 140 is associated with one growth tray 134, and a given outlet 146 within the array of outlets is not associated with any one growth tray 134.

[0076] In a further alternative embodiment, with reference to FIG. 7 the vertical growth tower 1 comprises a positive pressure unit 200 comprising a charging fan 202, an external intake valve 204, and an outlet 206 to the vertical growth tower 1, and the vertical growth tower 1 does not comprise an external vent, and the charging fan 202 is configured to maintain the pressure within the vertical growth tower 1. During use, if the pressure at the inlet 18 is determined to be greater than the target pressure range, the speed of the charging fan 202 is reduced to thereby allow the pressure within the vertical growth farm 1 to be reduced. If the pressure at the inlet 18 is determined to be less than the target pressure range, the speed of the charging fan 202 is increased to thereby increase the pressure within the vertical growth farm 1.

EXAMPLE 2

[0077] In an alternative embodiment with reference to FIG. 3, an HVAC system 100 comprises an inlet 102, an outlet 104, a controller 106, and a conditioning unit 108. The conditioning unit 108 comprise a variable speed fan 110, a cooling coil 112 (acting as a heat exchanger), a coolant reservoir 114 containing water (acting as a coolant), and a coolant pump 116. During use, air is drawn into the conditioning unit 108 via the inlet 102 by the variable speed fan 110, contacts the cooling coil 112 and passes out of the conditioning unit 108 via the outlet 104. Coolant is pumped through the cooling coil 112 by the coolant pump 116 in a circuit from the coolant reservoir 114 to the cooling coil 112 and back again. An inlet valve 122a and outlet valve 122b control the flow rate of water between the cooling coil 112 and reservoir 114. Temperature sensors 124a and 124b measure the temperature of the water flowing from the cooling coil and to the cooling coil respectively. The temperature of the cooling coil is controlled by opening or closing the inlet valve 122a and/or the outlet valve 122b in response to the temperature of the cooling water as measured by the temperature sensors 124a and 124b.

[0078] The inlet 102 comprises a temperature sensor 118a, and a humidity sensor 118b, and the outlet 104 comprises a temperature sensor 120a, a humidity sensor 120b. The controller 106 of the HVAC system 100 receives signals from the sensors of the inlet (118a, 118b) and the outlet (120a, 120b) of the HVAC system 100.

[0079] Prior to use, a target temperature, and a target humidity are set for the HVAC system 100. The dew point for the air passing entering the inlet 102 is determined by the controller 106 from the measured relative humidity and temperature recorded by the temperature sensor 118a and humidity sensor 118b at the inlet 102. During normal operation, the temperature of air entering the inlet 102 is higher than the target temperature, and therefore, the fan 110 urges the air through the conditioning unit 108 to contact the cooling coil 112 to thereby reduce the temperature of the air to the target temperature. In some instances, the flow rate of the coolant flowing through the cooling coil 112 may be changed to increase or reduce the rate at which heat is transferred between the air and cooling coil 112. If the humidity of the air entering the inlet 102 is determined to be higher than the target humidity the temperature of the cooling coil 112 is set to be below the determined dew point for the air entering the inlet 102 by increasing the flow rate of coolant flowing through the cooling coil 112 such that water condenses out of the air upon contact with the surface of the cooling coil 112 to thereby reduce the humidity of that air. If the humidity of the air entering the inlet 102 is determined to be at or lower than the target humidity the temperature of the cooling coil 112 is set to be above the determined dew point for the air entering the inlet 102.

[0080] The HVAC system may be used to condition the air of any enclosed space, such as that within an office building, an office space, an industrial building, a commercial building such as a hotel or similar, or within domestic buildings. The HVAC system may also be used to condition the air in an indoor growing environment, such as a greenhouse or a vertical farm.

EXAMPLE 3

[0081] The HVAC systems described herein may be operated manually, where the temperature of the cooling coil and the speed of the variable fan are set and adjusted until the desired temperature and humidity are reached and maintained.

[0082] The HVAC systems described herein may also be operated automatically, where the controller makes any necessary adjustments of the fan speed and cooling coil temperature in accordance with a program or algorithm stored in the memory of the controller.

[0083] A vertical growth tower 1 according to Example 1 further comprises a valve 44 associated with the outlet 10 associated with each growth tray 4 and the valve 44 can be variably opened or closed during use to control the flow of air into the associated growth tray 4. In addition, the vertical growth tower comprises a temperature sensor 46a, a humidity sensor 46b and pressure sensor 46c.

[0084] An example algorithm for controlling the temperature in the vertical growth tower is shown in FIG. 6.

[0085] Prior to operation the target conditions for the vertical growth tower 1 are set, including the target temperature (tower demand temp), the target humidity and target pressure. The controller then checks whether the temperature as recorded by the temperature sensor 46a meets the target temperature within 1° C.

[0086] If the tower temperature does meet the target temperature the algorithm returns to the checking state. If the tower temperature does not meet the target temperature, the controller determines whether the tower temperature is above the target temperature or below the tower target temperature.

[0087] If the tower temperature is above the target temperature, the controller checks to determine whether any of the outlet valves 44 are 100% open. If no outlet valves are 100% open, all outlet valves are opened a further 5% and the algorithm checks whether the tower temperature meets the target temperature within 1 degree after pausing for 15 minutes. If any of the outlet valves 44 are 100% open, the controller determines whether the delivery pressure (as determined by the pressure sensor 42c at the outlet 20) is 200 Pa above the tower pressure (as determined by the tower pressure sensor 46c). If the delivery pressure is determined to not be 200 Pa above the tower pressure, the fan speed is adjusted to adjust the delivery pressure to 200 Pa above the tower pressure. If the delivery pressure is determined to be 200 Pa above the tower pressure, the temperature of the air at the outlet 20 of the HVAC system 8 of the vertical growth tower 1 is checked. If the temperature of the air at the outlet 20 is determined to be above 5° C., the cooling coil temperature is reduced. After a pause of 15 minutes the controller reverts to the step of checking the tower temperature. If the temperature of the air at the inlet 18 is determined to not be above 5° C. the heat load created by the vertical growth tower is reduced by reducing the lighting output.

[0088] If the tower temperature is below the target temperature, the controller checks to determine whether all of the outlet valves 44 are greater than 40% open. If all outlet valves are greater than 40% open, the controller closes all outlet valves by 5% and the algorithm reverts to the tower temperature checking step after pausing for 15 minutes. If all of the outlet valves 44 are not greater than 40% open, the controller determines whether the delivery pressure (as determined by the pressure sensor 42c at the outlet 20) is 200 Pa above the tower pressure (as determined by the tower pressure sensor 46c). If the delivery pressure is determined to be 200 Pa above the tower pressure, the fan speed is adjusted to adjust the delivery pressure to 100 Pa above the tower pressure. If the delivery pressure is determined to not be 200 Pa above the tower pressure, the temperature of the air at the inlet 18 of the HVAC system 8 of the vertical growth tower 1 is checked. If the temperature of the air at the inlet 18 is determined to be below tower ambient temperature (typically between 23° C. to 32° C.), the cooling coil temperature is increased by reducing cooling by the chiller (cooling coil). After a pause of 15 minutes the controller reverts to the step of checking the tower temperature. If the temperature of the air at the inlet 18 is determined to not be below tower ambient temperature the heat load created by the vertical growth tower is increased by increasing the lighting output.

EXAMPLE 4

[0089] An alternative example, with reference to FIG. 5, a HVAC system 150 comprises an inlet 152, an outlet 154, a controller 156, an external intake valve 178, and a conditioning unit 160. The conditioning unit 160 comprise a variable speed fan 162, a cooling coil 164 (acting as a heat exchanger), a coolant reservoir 166 containing water (acting as a coolant), a coolant heating/cooling unit 168, a coolant pump 170, and a secondary coolant pump 172. During use, air is drawn into the conditioning unit 160 via the inlet 152 by the variable speed fan 162, contacts the cooling coil 164 and passes out of the conditioning unit 160 via the outlet 154. Coolant is pumped through the cooling coil 164 by the coolant pump 170 in a circuit from the coolant reservoir 166 to the cooling coil 164 and back again. Coolant is pumped pass the heating/cooling unit 168, by the secondary coolant pump 172

[0090] The inlet 152 comprises a temperature sensor 174a, a humidity sensor 174b and a pressure sensor 174c, and the outlet 154 comprises a temperature sensor 176a, a humidity sensor 176b and a pressure sensor 176c. The controller 156 of the HVAC system 158 receives signals from the sensors of the inlet (174a, 174b, 174c) and the outlet (176a, 176b, 176c) of the HVAC system 158.

EXAMPLE 5

[0091] A HVAC system used to condition a commercial space such as that shown in FIG. 8 may be operated automatically following an algorithm such as that shown in FIG. 9. The HVAC system may control the temperature and humidity of the commercial space.

[0092] The enclosed space 304 comprises a temperature sensor 310a and a humidity sensor 310b. The inlet 308 of the HVAC system 302 comprises a temperature sensor 314a and a humidity sensor 314b. The outlet 306 of the HVAC system 302 comprises a temperature 312a and a humidity sensor 312b.

[0093] Initially, the target humidity and temperature are set. The dew point of the air entering the inlet 308 of the HVAC system 302 from the enclosed space 304 is calculated from the temperature and the relative humidity recorded from the temperature sensor 314a and humidity sensor 314b in the inlet 308 of the HVAC system 302.

[0094] If the humidity is determined to be higher than the target humidity, the temperature of the cooling coil of the HVAC system is lowered to below the dew point of the air. If the humidity is determined to be lower than the target humidity, the temperature of the cooling coil is raised to be above the dew point of the air entering the inlet.

[0095] If the humidity is determined to be at the target humidity, the measured temperature is compared against the target temperature.

[0096] If the measured temperature is at the target temperature, the algorithm reverts to the beginning.

[0097] If the measured temperature is determined to be above the target temperature the speed of the fan is increased and the algorithm reverts to the beginning.

[0098] If the measured temperature is determined to be below the target temperature the speed of the fan is decreased and the algorithm reverts to the beginning.

[0099] While there has been hereinbefore described approved embodiments of the present invention, it will be readily apparent that many and various changes and modifications in form, design, structure and arrangement of parts may be made for other embodiments without departing from the invention and it will be understood that all such changes and modifications are contemplated as embodiments as a part of the present invention as defined in the appended claims.