NL2006419C2

NL2006419C2 - Climate control system.

Info

Publication number: NL2006419C2
Application number: NL2006419A
Authority: NL
Inventors: Antonius Hubertus Henricus Schmitz
Original assignee: Autarkis B V
Priority date: 2011-03-18
Filing date: 2011-03-18
Publication date: 2012-09-19

Description

Climate control system

TECHNICAL FIELD OF THE INVENTION

The invention relates to a climate control system for controlling the climate in a space for the growing of organisms such as plants.

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BACKGROUND OF THE INVENTION

Control systems for such buildings are generally known, in particular in the form of climate control systems for crop growth in greenhouses. The control systems known from the greenhouse crop growth are focused to the controlling of the climate in a 10 building in which the organism is formed by a plant. At such it is the intention to realize a inner climate or greenhouse climate which is optimally suited for the growth and development of the concerned organisms. Normally these greenhouse control systems depart from interaction between plant and environment, with in a control loop to control climate factors, mostly temperature, relative humidity, content, i.e. fraction of carbon 15 dioxide, amount of incident light, and air movement in the greenhouse.

There are several constraints that have to be taken in to account to have an optimal climate. The temperature in the greenhouse should be kept within a predefined range to have growth. The CCh-content should be high enough to allow the process of photosynthesis. The relative humidity should be high enough such that the crop does not 20 wither, but should not come above 85% as fungi will grow rapidly in such an environment and will affect the crop which decreases the productivity of the crop.

New cultivation revolves around the integration of climate and energy systems in a conditioned cultivation environment also known as closed greenhouses. Climate control in the conditioned greenhouse is fully automated, giving the grower 25 maximum control over the crucial growth factors of temperature, relative humidity and C02.

This optimal climate regulation has many advantages. The primary advantage is that growers can realise a production increase of up to 20%. A considerable reduction in energy consumption is another important advantage. In practice, energy 30 consumption in greenhouses using the new cultivation methods is 15% to 20% lower the conventional greenhouses with windows.

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The closed greenhouse can store heat in summer for use in winter. The greenhouse basically functions as a solar collector. The closed windows reduce the risk of infection, and also save water, as water that evaporates is recovered through condensation.

A horticulture greenhouse is a large solar collector. However, the influence 5 of the sun is not divided evenly over the seasons. In spring and summer the greenhouse gets too much heat, whereas in winter there is not enough heat. In currently known closed greenhouses, the surplus solar heat is removed from the greenhouse with the aid of an air conditioning unit. This heat is then stored in an aquifer, an underground layer of soil or rock that functions as a natural well. In the winter the warm water from the aquifer is 10 pumped up and heated to 50°C using a heat pump. The cold water generated during the heating process is stored in a cold well. In the summer this cold water is used to cool and dehumidify the greenhouse. The construction of known closed greenhouses is expensive as an aquifer is needed for heat storage.

15 SUMMARY OF THE INVENTION

The object of the invention is to provide a new climate control system for use in a space of growing organisms which allows to realize at least one of: production increase of crops, reduction of energy consumption.

According to the invention, this object is achieved by a system having the 20 features of Claim 1. Advantageous embodiments and further ways of carrying out the invention may be attained by the measure mentioned in the dependent claims.

According to the invention, the system comprises a PCM unit positioned in the air channel wherein the PCM unit comprises a phase change material with a melting temperature which is at the desired minimum space temperature and wherein the outlet 25 side is configured to direct an airflow along surfaces of the growing organisms and the control part is configured to control the air-displacement system in response to measured temperature and relative humidity in the space.

The invention is based on the recognition that in greenhouses the temperature and humidity heavily depends on the amount of solar radiation. The 30 temperature will increase due to the solar radiation and the humidity increases due to the evaporation of the plants. The humidity normally increases faster than the temperature resulting in a relative humidity above 85%. This is however not desired is this is a condition wherein fungi will grow rapidly and consequently infect the plants. In 3

conventional greenhouses, the windows are opened and both heat and vapour will leaf the greenhouse. By using a PCM unit, the moment at which the windows have to be opened can be delayed and even prevented. Guiding the air with a relative humidity of 85% in the range of 20°C - 28°C along a PCM material with a melting temperature at for example 5 20°C, will cool down air temperature resulting in condensation on the surface of the PCM

material. The air cooled to about the PCM melting temperature is subsequently blown in to the space along the surfaces of the plants. In this way, moisture or water damp produced by the plant is removed from the air and additionally heat is extracted from the space an stored in the PCM material. As soon as the space temperature falls below the melting 10 temperature of the PCM-material, the heat stored in the PCM material could be extracted from the PCM unit by having an air flow along the surface of the PCM unit and heating the airflow. In this way, the heat stored in the PCM material is used to heat the space and less energy is needed to keep the space at a desired minimum temperature, for example by means of a heating boiler or heat pump. Furthermore, the power needed to displace the air 15 is far less than the power needed to displace water when using an aquifer.

In an embodiment of the invention, the outlet side of the air treatment part is located at a top side of the air-treatment part and wherein the outlet side is configured for generating an airflow in essentially a vertical direction along the surfaces of the organisms. By blowing cooled and dried air along the surfaces of the plant, the plants are cooled by 20 the temperature of the air and could better release moisture as the relative humidity of the air blown along the surface is lower than the relative humidity of 85% of air in other places in said space. Both effects improves the growing conditions of a plant.

In an embodiment of the invention, the outlet side comprises nozzles configured to generate a turbulent airflow by mixing a primary airflow coming out of a 25 nozzle and a secondary airflow of external air in said space, which secondary airflow is induced by the primary airflow. By mixing the cooled and dried air with the air in the space, the relative humidity of the air decreases allowing the plant to release moisture. Furthermore, the nozzles increases the speed of the airflow leaving the outlet side, resulting in air movement in essentially the whole space and along all surfaces of the 30 plants.

In an embodiment of the invention, the PCM unit is arranged in the form of essentially parallel panels between which the airflow can flow. This increases the capacity to dehumidify the air. In an embodiment, the panels are positioned vertically. This has the 4 advantage that condensation will go down by means of gravity. In another embodiment, the parallel panels form air channels which slope down in direction of the airflow in the air channels between panels. Both the slope down and the airflow direction will ensure that condensate in the air channels will be drain away and removed from the condensation 5 surface of the PCM-unit. Preferably, the PCM unit has a surface adapted to the volume of th space. These features defines the maximum instantaneous dehumidify/cooling capacity of the PCM unit. Preferably, the PCM unit comprises a predefined volume of PCM material per m3 of space. This feature determines the heat storage capacity of the air treatment part. Preferably, the PCM unit comprises PCM-material with a melting point of 10 18°C - 25°C degrees Celsius. This feature defines the operating temperature of the system.

In an embodiment of the invention, the air-treatment device further comprises air filters which are provided in the air channel. This feature enables to reduce the amount of pathogenic organisms in the air in the space of the growing organisms.

15 In an embodiment of the invention, the control part is configured to control the air displacement device such that the relative humidity in the space is in the range of 75 - 85%, preferably in the range of 80 - 85%, more preferably in the range of 83 - 85%.

In an embodiment of the invention, the control part is configured to control the air displacement device such that an increase in relative humidity above 85% increases 20 the airflow through the air displacement device.

In an embodiment of the invention, the control part is configured to control the air displacement device such that an increase in temperature in the space increases the airflow through the air displacement device.

It is a further aspect of the invention to provide an improved method of 25 controlling the climate of a space with growing organisms, such as plants, which improves the growing conditions of the organisms and reduces the required power consumption.

The method comprises providing in said space an arrangement comprising all essential technical features of a climate control system according to the invention, providing growing organisms in said space such that the airflow out of the system flows along 30 surfaces of the growing organisms; and, controlling the air-displacement system in response to measured temperature and relative humidity in said space.

It will be clear that the various aspects mentioned in this patent application may be combined and may each be considered separately for a divisional patent 5 application. Other features and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawing which illustrate, by way of example, various features of preferred embodiments of the invention.

5 BRIEF DESCRIPTION OF THE FIGURES

These and other aspects, properties and advantages of the invention will be explained hereinafter based on the following description with reference to the drawings, wherein like reference numerals denote like or comparable parts, and in which: FIG. 1 illustrates a first embodiment of a climate control system according 10 to the invention when dehumidifying the air in a space with growing plants; FIG. 2 illustrates the first embodiment of a climate control system according to the invention when releasing stored heat; FIG. 3 illustrates a second embodiment of a climate control system according to the invention; 15 FIG. 4 illustrates the use of a climate control system according to the invention in a greenhouse; and FIG. 5 illustrates the working conditions of a climate control system according to the invention.

20 DESCRIPTION OF EMBODIMENTS

Figure 1 illustrates an exemplar first embodiment of a climate control system 1 according to the invention for controlling the climate of a space with growing organisms 2. In context of the present invention, growing organisms are organisms in which photosynthesis occurs. Photosynthesis is a process that converts carbon dioxide into 25 organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photo synthetic organisms are called photoautotrophs, since they can create their own food. In plants, algae, and cyanobacteria, photosynthesis uses carbon dioxide and water, releasing oxygen as a waste product. The space is a space filled with air in which sunlight can enter or in 30 which light and heat is generated by lamps to simulate the sun. An examples of a space in which sunlight can enter is a greenhouse.

The climate control system 1 comprises an air-treatment part 11 and a control part 12 configured to control the air-treatment part 11 in response to measured 6 temperature and relative humidity in the space. The temperature and relative humidity are sensed by corresponding sensors 13 which could be integrated in the control part 12 or positioned remote from the control part 12 as shown in FIG. 1. In FIG. 1 a plant 2 is positioned above the air-treatment part 11. The air-treatment part could comprises a 5 support for carrying a row of plants. The support could be the upper side of the air-treatment part 11.

The air-treatment part 11 comprises an air channel 1 lc having an inlet side 11a configured to take in air from the space and an outlet side 1 lb configured to release air to said space. An air displacement device 1 Id is positioned in the air channel between the 10 inlet side and outlet side. The air-displacement device is configured for generating an airflow from the inlet side to the outlet side through the air channel 11c. The air displacement device is a powered device used to create a flow within a gas. The air displacement device could be in the form of an axial fan, centrifugal fan, crossflow or tangential fan. The flow generated by the air displacement device is variable by 15 controlling the rotation speed of the fan. The control part 12 controls the rotation speed of the fan and as a result the speed of the air flow through the air-treatment part 11.

The air-treatment part 11 further comprises a PCM unit lie positioned in the air channel lie. The PCM unit lie comprises a phase change material with a melting temperature which is at the desired minimum space temperature. For most plants in a 20 greenhouse the optimal temperature for growing is in the range of 20 - 28°C. A melting temperature in the range of 18°C-25°C, in an embodiment even in the range of 19°C -22°C is regarded suitable to provide the air-treatment part 11 the required characteristics, i.e. the capability to dehumidify air.

The PCM unit 1 le is arranged in the form of essentially parallel panels 1 lei 25 between which the airflow can flow. In the first embodiment, the panels are positioned vertically and the air flows vertically upwards along the surface of the panels 1 lei through air channels 1 le2 between the panels.

The inlet side 1 la is located at the lower end of the air-treatment part and could be provided with a grate. The outlet side 1 lb is located at a top side of the air-30 treatment part. The outlet side 1 la is configured for generating an airflow in essentially a vertical direction along the surfaces of the organisms. This embodiment is particularly suitable for plants which extend to the roof of the space, such as tomato, cucumber, paprika and eggplant. In case the plants are relatively low with respect to the space, the outlet side 7 1 lb could be in the form of tubes with small openings to distribute the treated air across the area of the space where plants are positioned. Tubes to distribute Carbon dioxide CO2 in conventional greenhouses could be used for this.

The outlet side 1 lb shown in FIG. 1 comprises nozzles configured to 5 generate a turbulent airflow by mixing a primary airflow coming out of a nozzle and a secondary airflow of external air in said space. The secondary airflow is induced by the primary airflow. In FIG. 1 the arrows 3b indicate the primary airflow coming out of the nozzles 1 If and the arrows 3 c indicate the secondary airflow induced by the primary airflow 3 a. The total area of the opening(s) at the inlet side 1 la is larger than the total area 10 of the openings of the outlet side lib when nozzles are used. As a consequence, the speed of the outflow of air at the outlet side 1 lb is much faster than the inflow of air at the inlet side 11a.

The air treatment part 11 further comprises a drain output 1 lg to drain condensate generated when dehumidifying the air in the space.

15 An air filter (not shown) could be provided at the inlet side 1 la to clean the air and to prevent that dust and other contaminants could pollute the air-treatment device internally.

FIG. 4 illustrates the working environment of the climate control system according to the invention. A greenhouse 4 forms the space wherein plants 2 grow. The 20 air-treatment part 11 generates and air flow to circulate the air through the space. The plants are positioned above the air-treatment part 11 such that the air flow 3b coming out of the air-treatment part 1 flows along the leaves of the plants. In this way, the plants are cooled by the airflow. Furthermore, the plants could release heat by evaporation wherein the vapour is taken away in the airflow. In FIG. 4 the air treatment part 11 generates an 25 upward airflow with essentially vertical direction through the leaves of the plants 2. When reaching the roof of the greenhouse, the airflow 3 bends downward and goes down to the inlet of the air-treatment device 11. In this way the air is circulated in the space of the greenhouse 4. A control unit 12 and sensors 13 are provided in the greenhouse to generate a control signal to control the air-treatment part 11, more particularly the rotation speed of 30 the air displacement device in the air-treatment part 11.

The climate control system according to the invention functions as follows. FIG. 1 illustrates the condition at day time when the sun is shining in the greenhouse. The temperature will rise due to the sunlight and the plants will evaporate to cool their leaves.

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As the greenhouse is closed, both the temperature and relative humidity will rise. When the temperature is in the range of 20 - 28°C and the relative humidity is high, i.e. 85%, the air displacement device lid will be controlled by the control part 12. At the inlet side 1 la, a warm airflow 3 a will enter the air treatment device and will flow through the PCM unit 5 lie. The PCM unit lie having a temperature corresponding to the melting temperature of the PCM material in the PCM unit, will cool the air and the relative humidity of the cooled air will rise in the PCM unit to saturation (100% relative humidity). The water damp will condensate at the surface of the PCM-unit and the condensate will drip from the PCM-unit. Furthermore, the heat from the air flow will be stored in the PCM-material. The cooled air 10 is subsequently blown out of the treatment part 11 and mixed with a secondary airflow 3c of warm air from the space. The mixed airflow has a relative humidity which is lower than the relative humidity of the airflow 3a at the inlet side 1 la and the secondary airflow 3c. Furthermore, initially the temperature of the mixed airflow will be lower than the average temperature in the greenhouse. In this way, heat is extracted from the space and stored in 15 the PCM material. Furthermore, the condensation process in the air-treatment part 11 extracts heat from the airflow and consequently from the space in the greenhouse.

FIG. 2 illustrates the condition at night or in the event there is not enough solar energy in the form of sunlight to heat the temperature to the minimal desirable temperature in the space. If the temperature in the space decreases to a temperature below 20 the melting temperature of the PCM-material in the PCM unit, the control part controls the air-displacement device 1 Id to generate an airflow through the air-treatment part 1 from the inlet side to the outlet side. Now a flow 3a’ of cold air is taken in at the inlet side, warmed up to the melting temperature of the PCM-material and supplied to the outlet side of the air-treatment part 11. The heated air is subsequently blown out of the treatment part 25 11 and mixed with a secondary airflow 3c’ of cold air from the space. The temperature of the mixed airflow will be higher than the average temperature in the greenhouse. In this way, heat is extracted from the PCM material, given back to the space and the temperature of the air in the space could be kept at temperature as long as the PCM-material is capable to transfer stored heat to the airflow through the PCM-unit. With respect to a conventional 30 greenhouse, by using the invention, the moment at which an external heat source has to be used can be postponed, which corresponds to a energy saving.

FIG. 3 illustrates a second embodiment of a treatment part 11 of a climate control system according to the invention. The second embodiment differs from the first 9 embodiment in that the flat panels 1 lei of the PCM-unit lie are not positioned vertically but in a horizontal manner. In this embodiment, a horizontal airflow is generated between two neighbouring panels. To prevent obstruction in the air channels or accumulation at the horizontal surfaces of the PCM-panels 1 lei due to condensate, preferable the panels form 5 air channels which slope down in direction of the airflow between the PCM-panels.

The control part 12 of the climate control system according to the invention could be in the form of a stand-alone processing unit or be integrate in the software program of a climate control computer of the greenhouse.

The control part 12 controls the climate in the space in a way having at least 10 one of the following characteristics: At day time, the relative humidity in the space is kept in the range of 75 - 85%, preferably in the range of 80 - 85%, more preferably in the range of 83 - 85%; an increase in relative humidity above 85% increases the airflow through the air treatment device; an increase in temperature in the space increases the airflow through the air displacement device; when the space temperature falls below a desired minimum 15 temperature, an airflow is generated through the air treatment device to extract heat from the PCM-material.

FIG. 5 shows a graph illustrating the functioning and climate conditions of the climate control system. The vertical axis corresponds to the air temperature in the space to be controlled. The horizontal axis X[g/kg] corresponds to the humidity ratio. The 20 humidity ratio X[g/kg] can be expressed as the ratio between the actual mass of water vapor present in moist air - to the mass of the dry air. Humidity ratio is normally expressed in kilogram or pounds of water vapor per kilogram or pounds of dry air. Line 50 is the saturation curve or dew point temperature curve which corresponds to a relative humidity of 100%. Line 52 indicates the desired climate condition wherein the relative 25 humidity cpj in the space is 85% in a particular temperature range. In point A, the temperature is 20°C and relative humidity is 85% in the space of the growing plant. In point B, the temperature is 28°C and relative humidity is 85%. In point B, defining the maximum desired temperature in the space, the control part controls the air displacement device to provide the highest airflow from the inlet to the outlet of the air-treatment part, 30 resulting in the highest possible dehumidification of and cooling capacity of the air in the space. As the air treatment part performs both cooling and dehumidification, the rotation speed of the air displacement device could be controlled such that when the temperature in 10 the space decreases the relative humidity is kept at 85% or any other desired relative humidity.

Advantages of the climate control system according to the invention is that during the heating season, the greenhouse could be kept closed. A surplus of solar energy 5 can temporarily be stored in the PCM-unit for use at a later moment when the amount of solar energy is to low to keep the space temperature above a desired minimum. No waste of generated CO2 due to open windows to cool the space. The heat storage capacity of the PCM-unit could be used at day time to store the heat generate to produce CO2. The stored heat in the PCM-unit could be used at night to discharge the PCM-unit and to heat the 10 space wit plants. The condensate could be reused in the greenhouse for growing the plants.

In the embodiments given above, the PCM-unit is positioned in the air channel from inlet side to outlet side between the air displacement device and the inlet side. It might be clear that it is also possible to have the PCM unit positioned between the air displacement device and the outlet side.

15 The measures described hereinbefore for embodying the invention can obviously be carried out separately or in parallel or in a different combination or if appropriate be supplemented with further measures; it will in this case be desirable for the implementation to depend on the field of application of the device. The invention is not limited to the illustrated embodiments. Changes can be made without departing from the 20 idea of the invention.

Claims

1. Climate control system (1) for controlling the climate of a room with growing organisms, wherein the system comprises an air treatment part (11) and a control part (12) which is adapted to control the air treatment part, wherein the air treatment part comprises: - an air duct (11c) with an inlet side (11a) adapted to allow air into space and an outlet side (11b) adapted to allow air into the space; - an air displacement device (member) which is placed in the air channel between the inlet side and the outlet side and is adapted to generate an air flow from the inlet side to the outlet side through the air channel; characterized in that the system further comprises a PCM unit (lie) disposed in the air duct wherein the PCM unit comprises a phase change material with a melting temperature 15 which is at the desired minimum room temperature, and the control part is arranged around the air treatment part to control in response to measured temperature and relative humidity in the room.

2. System as claimed in claim 1, characterized in that the outlet side is positioned on an upper side of the air treatment part and wherein the outlet side is adapted to generate an air flow substantially in a vertical direction along the surfaces of the organisms.

3. System as claimed in claims 1 or 2, characterized in that the outlet side comprises outlet pieces adapted to generate a turbulent air flow by mixing a primary air flow coming out of an outlet piece and a secondary air flow of external air into the room wherein the secondary air flow is induced by the primary air flow.

A system according to any one of claims 1-3, characterized in that the PCM unit is arranged in the form of substantially parallel panels between which the air flow can flow.

A system according to claim 4, wherein the parallel panels form air ducts that run in the direction of the air flow in the air ducts.

6. System as claimed in any of the claims 1-5, wherein the PCM unit has a surface adapted to the volume of the room.

The system of any one of claims 1 to 6, wherein the PCM unit comprises 0.0001 - 0.01 m3 of PCM material per m3.

The system of any one of claims 1 to 7, wherein the PCM unit comprises PCM material with a melting point of 18-25 degrees Celsius.

The system of any one of claims 1-8, wherein an air filter is provided in the air duct. 15

System as claimed in any of the claims 1-9, wherein the control part is adapted to control the air displacement device such that the relative humidity in the room is in the range of 75 - 85%, preferably in the range of 80 - 85% , even more preferably in the range of 83 - 85%. 20

The system of claim 11, wherein the control member is adapted to control the air displacement device such that an increase in relative humidity above 85% increases the air flow through the air displacement device. 25

12. System according to any of claims 10-11, wherein the control part is adapted to control the air displacement device such that an increase in temperature in the room increases the air flow through the air displacement device. 30

A method for controlling the climate of a room with growing organisms, the method comprising providing an arrangement in the room comprising all technical measures of a climate control system according to any of claims 1-12, providing growing organisms in the space so that the air flow from the system flows along surfaces of the growing organisms; and, controlling the air displacement device in response to measured temperature and relative humidity in the room. 5

An air handling unit comprising all technical measures of an air displacement device according to any of claims 1-9.

15. Control unit adapted to control an air displacement device 10 according to one of claims 1-9, comprising all technical measures of a control part according to one of claims 10-12.