WO2011045470A1

WO2011045470A1 - Method and apparatus for cooling down cooling water needed for drying and cooling of greenhouse air

Info

Publication number: WO2011045470A1
Application number: PCT/FI2010/050790
Authority: WO
Inventors: Markku Haukioja; Kati Haukioja; Esko Huhta-Koivisto; Jukka Huttunen; Antti Jalava; Jarmo Sainio
Original assignee: Novarbo Oy
Priority date: 2009-10-13
Filing date: 2010-10-11
Publication date: 2011-04-21
Also published as: EP2488009A1; EP2488009A4; FI20096057A0

Abstract

The invention relates to an antimicrobial composition containing coniferous resin acids and/or their derivates. The invention also relates to an antimicrobial polymer composition comprising coniferous resin acids and/or their derivates and processes for preparing thereof. The invention also relates to the use of the derivates of coniferous resin acids as an antimicrobial agent.

Description

Method and apparatus for cooling down cooling water needed for drying and cooling of greenhouse air

FIELD OF THE INVENTION

This invention relates to an arrangement and method, enabling the refrigeration of cooling water needed for dehumidifying and cooling greenhouse air, as well as to a greenhouse equipped with an arrangement of the invention.

DESCRIPTION OF THE PRIOR ART

An objective in modern greenhouse production is to regulate the greenhouse climate for making it as consistent as possible with conditions optimal from the standpoint of plant growth. In optimal growth conditions, depending on the cultivated plant, the greenhouse has a temperature of about 18-30°C, an air moisture of about 60-90%, and a carbon dioxide concentration of more than 1000 ppm. The optimal growth conditions call for a good management of temperature, moisture, and carbon dioxide concentration.

In a commonly used greenhouse, the climate is regulated by means of vents and/or fans. In this case, the surplus heat supplied by solar radiation is removed from the greenhouse by means of ventilation. The demand of at least partial ventilation exists also in Finland for about 8 months of the year.

The cooling of greenhouse air is enhanced by spraying the room with water in a mist as fine as possible. In the process of spraying, the evaporating water absorbs heat from greenhouse air and increases the air humidity. The effective use of spraying for the cooling of greenhouse air usually requires also ventilation in order to enable a removal of moist air from the room and to enable the spraying to continue. Typically, the maximum amount of sprayed water is less than 0,5 liters/hour/m² of greenhouse. Today's greenhouses do not enable a carbon dioxide level optimal from the standpoint of plant growth to be sustained during the period of a high radiation level, at which time it would offer a maximum benefit. The carbon dioxide escaping along with ventilation air would increase the required amount of carbon dioxide to such an extent that its distribution is not economically viable. Thus, during the season of a high radiation level, the situation is usually such that, in conditions most favorable in terms of plant growth, it will be necessary to settle in the carbon dioxide concentration of greenhouse air for an outdoor air level (about 380 ppm) instead of a carbon dioxide level (500 ppm to 1500 ppm) that would be favorable from the standpoint of plant growth. Due to the above, the plant growth in greenhouses today falls short of what it could be if there was a way of sustaining a high carbon dioxide level in greenhouse air even during the period of a high radiation level. In Finland, for example, the best growth results are achieved in late winter when the radiation level is high and the outdoor air is sufficiently cold for greenhouses not to require cooling by ventilation, thus enabling a raised carbon dioxide level to be sustained in greenhouses. In warmer climate conditions, it is not generally possible to reach equally high growth results.

For the above reasons, attempts have been made in different parts of the world to develop various types of closed greenhouse. In the closed greenhouse, indoor air is almost sealed from outdoor air. Outdoor air is not allowed through vents, nor is it blown by fans into the greenhouse, the surplus heat being conducted out by other means. The carbon dioxide needed by plants is supplied by technical production and its concentration is preferably raised to a level of not less than 500 to 1500 ppm. Because of an optimal climate regulation, the closed greenhouse is considered an ideal solution for the cultivation of plants. In closed greenhouse solutions, it is water which is most commonly used as a carrier and storage of energy. Due to a low temperature and a large amount of energy, water is needed in abundance. A method (WO

00/76296A1) developed in Holland involves the utilization of aquifers as energy stores. The method requires major investments and is only applicable in regions in which such aquifers exist. In the Finnish Novarbo system, the heat of water warmed up in a greenhouse and circulating in the system is evaporated to outdoor air in a separate cooling basin. A greenhouse system, having its climate regulation implemented according to an at least partially closed system, has been the object of several international patent applications. It is prior knowledge to conduct the cooling and dehumidifying of greenhouse air with cool water. Patent applications EP20070712613 and EP20050818322 describe methods and systems for the dehumidifying and cooling of greenhouse air by means of water cooler than the dew point temperature of the room air, as well as greenhouses equipped with technology consistent with the patent.

PROBLEMS IN THE STATE OF THE ART

Prior known climate management solutions for a closed or semi-closed greenhouse are relatively easy to carry out in conditions with an abundant supply of low-temperature cooling water. However, commercial greenhouse production is predominantly located in regions where sufficiently cold cooling water is not, at least not constantly, available. In many instances, available water can even in this case be refrigerated for cooling water by means of evaporators placed outside the greenhouse. Prior known are solutions, among others, in which cooling water is refrigerated in a fan equipped evaporator or a basin installed outside the greenhouse.

In the fan equipped evaporator, water is refrigerated by establishing a contact between air and water in a powerful air flow produced by fans. In basin solutions, the refrigeration is provided by spraying water into the air at the surface of a cooling water basin by means of jets or propeller evaporators placed in the basin.

The water used in refrigeration can also be cooled by means of cooling towers common in industrial use.

The problems with prior known greenhouse air dehumidification and refrigeration are largely associated with the production of cooling water to be used:

A problem with solutions based on the fan equipped evaporator is the high energy consumption and high noise level of fans.

In basin solutions, the problems relate to the soiling and algal growth of open basins, as well as to the area demand of basins. The

comparatively large basin area also increases a solar radiation load, which in many instances raises the necessary demand of cooling capacity by 10 to 30%.

As a result of small temperature differences, the use of cooling towers requires sizable equipment, involving usually such a high capital investment cost that its use in the cooling solutions of greenhouses is unviable.

Prior known are also methods, in which the greenhouse is cooled by spraying water onto the greenhouse roof or by conducting cool water into the intermediate layer of a roofing material for cooling the same. In prior known methods, the water itself is not an object of refrigeration, nor is it used in equipment within a greenhouse for cooling the greenhouse air. In these methods, the indoor air cooling effect of water sprayed on the roof is restricted to cooling the roof surface instead of cooling the water sprayed on the roof and its use in greenhouse air dehumidification and refrigeration equipment. DESCRIPTION OF THE INVENTION

This patent application describes a method for the refrigeration of cool water needed in cooling and dehumidifying the air of a closed or semi-closed greenhouse. Likewise described is an arrangement for implementing the method and a greenhouse equipped with an arrangement of the invention.

The arrangement according to the invention is characterized in that the water collection devices are provided on the greenhouse roof or in its vicinity so as to enable at least some of the water sprayed onto and collected from the roof to be conveyed gravitationally to air cooling and dehumidifying equipment present inside the greenhouse and/or further downward by spraying with nozzles included in the collection devices.

The method according to the invention is characterized in that, in the method, warmed-up refrigeration water, which has been used for the dehumidifying and cooling of greenhouse air, is conveyed up onto a roof of the greenhouse and refrigerated by spraying it over an external surface of the roof, and also water, which has been refrigerated by spraying, is recovered for reusing it for dehumidifying and cooling the indoor air of the greenhouse.

The greenhouse according to the invention is characterized in that the collection devices for water sprayed over the greenhouse roof are provided on the roof or in the vicinity of the roof so as to enable at least some of the water sprayed over and recovered from the roof to be conveyed directly to cooling equipment present inside the greenhouse and/or that the water collection devices present on the greenhouse roof are fitted with nozzles for spraying the cooling water further downward.

In a method of the invention, the water used for drying and cooling the air space of a greenhouse is refrigerated by spraying it into the air on the greenhouse roof and by collecting water sprayed onto the roof to be reused for cooling and dehumidifying the indoor air of the greenhouse. In the method described in this invention, the greenhouse roof functions as a collector of water to be sprayed and partly as an evaporator, the cooling of a roofing material further enhancing the conduction of heat out of the greenhouse.

The cooling capacity of water in a method of the invention is based on the evaporation of subsequently sprayed water from the absorbing energy, and on the other hand, on the conduction of heat from the cooling water to outdoor air. The method according to the invention is applicable whenever the wet-bulb temperature of outdoor air is lower than the desired

temperature of cooling water. The required cooling water temperature depends on desired greenhouse conditions. For example, in the cultivation of cucumber, the refrigeration of a greenhouse can be effected by using cooling water with a temperature of about 20°C. The lower the wet-bulb

temperature of outdoor air the easier it is to chill water to this temperature. The method is not generally applicable in tropical conditions, in which the outdoor air has both a high temperature and a high humidity.

Performance of the method can be improved by using a cooling water storage whose water can be subjected also to e.g. nighttime refrigeration, at which time the interior of a greenhouse does not generally need cooling and conditions for chilling the water sprayed onto the greenhouse roof are usually more favorable than during the day. The water sprayed or conveyed onto the greenhouse roof can also be sprayed from eave-mounted collection devices downward partially or entirely by gravity, whereby the water is further cooled by evaporation. In certain conditions, this may be necessary for enhancing the refrigeration of water. On the other hand, when there is not a major urgency for the refrigeration of water, the spraying of water from the eaves level into a gutter present at the lower part of a greenhouse wall may be sufficient for chilling the water without spraying water at all onto the greenhouse roof. The method can also be supplemented by the use of a heat pump for enhancing the refrigeration of cooling water and/or for recovering the energy of cooling water and making use of it in heating. The method comprises cooling simultaneously both water to be sprayed on the roof and the roof surface of a greenhouse. The roof surface cooling makes a contribution to greenhouse climate management. For the most part, however, the arrangement has its effectiveness based on the refrigeration of water so as to enable its use within a greenhouse for cooling and drying the indoor air particularly in applications, wherein the water sprayed on the roof is conveyed directly by gravity to indoor greenhouse air cooling systems, such as Novarbo, thereby minimizing the energy used for pumping water.

It is a characterizing feature that, in a method of the invention, the amount of water to be sprayed onto the roof is very large - typically 50 to 150 liters per square meter of greenhouse in an hour. The amount of sprayed water can be regulated according to outdoor air conditions for attaining a required cooling performance. The invention enables making use of a roof surface in its entirety or just partially, depending on the conditions and indoor cooling system.

The arrangement according to the invention comprises an assembly of devices necessary for carrying out the method. The arrangement includes: Devices for conveying water onto the roof of a greenhouse (Fig. 1, 1), devices for spraying water over the greenhouse roof, as well as a collection system by means of which the water sprayed over the roof is recovered and re-conveyed into the greenhouse interior to be used in equipment intended for the cooling and dehumidifying of indoor air. Operation of the

arrangement can be controlled by means of automatics which can be interconnected with other greenhouse control automatics. The greenhouse according to the invention is a closed or semi-closed greenhouse, which is equipped with devices of the invention.

The solution according to the invention can be applied in a variety of configurations within the scope of the appended claims.

MERITS OF THE INVENTION OVER THE STATE OF THE ART

The method and arrangement according to the invention enable cooling water used for the cooling and air humidity management of a partially or totally closed greenhouse to be refrigerated in a substantially more

economical manner than by using prior known water cooling methods.

The essential merits gained by the invention over the current state of the art are:

^■ The refrigeration of water can be effected by making use of existing greenhouse structures and an extensive greenhouse roof surface area as a collector of sprayed water. The only necessary accessories are devices by which the water is conveyed onto the greenhouse roof and sprayed over an external surface of the roof, as well as collection devices by which the sprayed water is recovered and conveyed to be used in equipment intended for the cooling and humidity management of the greenhouse indoor air.

^■ The solutions do not require separate sprayed water collection

systems or extensive water basins, the use of which leads to a problem of water contamination and algal growth, as well as a radiation load applied over the surface area of a basin. In the solutions according to the invention, refrigeration is only needed for the heating effect of radiation applied to the greenhouse itself.

^■ The water storage included in the invention can be protected from light, whereby maintaining its cleanliness becomes substantially easier.

^■ The solutions according to the invention do not require fans for

generating a water-cooling air flow. By virtue of water spraying, the roof of a greenhouse inherently develops a powerful air circulation. In addition, the evaporation-encouraging wind is often stronger up on the roof than at ground level.

■ In the solutions according to the invention, a cooling effect is attained in two different ways by water sprayed over the roof of a greenhouse. On the one hand, the water sprayed over the roof cools the

greenhouse roof and thereby the greenhouse indoor air. On the other hand, the sprayed water refrigerates - depending on the dimensions of jets - towards the wet-bulb temperature of outdoor air, and the thereby chilled water can be used for the cooling and humidity management of greenhouse indoor air.

■ The method according to the invention enables reducing greenhouse thermal losses, e.g. during a cold night when the temperature of outdoor air is substantially lower than that of sprayed cooling water.

APPLICATION EXAMPLES The subsequently presented examples are by no means limitative regarding ways of implementing solutions of the invention. The examples are only intended for detailing a few forms of application for the invention, which, in addition to the exemplified cases, can be freely modified within the scope of the appended claims.

Example 1. Fig. 1 shows an arrangement of the invention in a basic solution, wherein, in order to convey water which has warmed up within a greenhouse, the arrangement includes a piping (1) by means of which the cooling water, which has warmed up within a greenhouse, can be conveyed up onto a roof (6) of the greenhouse. The arrangement is further provided with nozzles (2) by means of which the cooling water can be sprayed over the greenhouse roof, as well as a collection gutter (3) by means of which the water, which has been sprayed over the roof and which has chilled during the spraying process, can be recovered and conveyed by way of a piping (4) to cooling equipment present inside the greenhouse or into a basin or water storage (5) associated with the greenhouse.

Example 2. Fig. 2 shows an arrangement comprising, in addition to the devices described in example 1, a piping (7) which enables cooling water to be conveyed gravitationally from the collection devices (3) of water sprayed over the roof (6) directly to nozzles (8) included in cooling equipment present inside the greenhouse.

Example 3. Fig. 3 shows an arrangement comprising, in addition to the devices described in example 1, nozzles (9), which are fixed to a bottom of the gutter (3) present at the eave level of a greenhouse and which enable cooling water accumulating in the gutter to be further sprayed outside the greenhouse along a wall (10) into a collection gutter (11) present at a bottom part of the wall, and to be further conveyed therefrom along a piping to cooling equipment present inside the greenhouse. Example 4. Fig. 4 shows an arrangement, wherein water to be refrigerated is conveyed by means of a piping (1) up onto a roof (13) of the multi-ridge or so-called block greenhouse and sprayed over the roof by means of nozzles (2) included in the piping. The refrigeration of water only takes place over a portion of the block house roof, and the collection of water is effected by making use of a rainwater collection system, the water returning directly to an internal greenhouse cooling system or into a basin or water storage (12) present under the greenhouse.

Claims

1. An arrangement for dehumidifying and cooling greenhouse air by means of cool water, said arrangement comprising devices (1), which enable warmed-up cooling water, which has been used for drying and cooling the indoor air of a greenhouse, to be conveyed up onto a roof (6; 13) of the greenhouse, and devices (2) for spraying the water over an external surface of the roof, as well as collection devices (3), which enable sprayed water to be recovered for use in dehumidifying and cooling equipment present inside the greenhouse, characterized in that the water collection devices (3) are provided on the greenhouse roof (6; 13) or in its vicinity so as to enable at least some of the water sprayed over and collected from the roof to be conveyed gravitationally to air cooling and dehumidifying equipment (8) present inside the greenhouse and/or further downward by spraying with nozzles (9) included in the collection devices (3).

2. An arrangement as set forth in claim 1, characterized in that the spraying devices (2) included in the arrangement and present on the greenhouse roof (6) are adapted to spray water in upward direction towards a ridge of the greenhouse or in downward direction from a ridge of the greenhouse over one or two sloping surfaces.

3. An arrangement as set forth in claim 1, characterized in that the spraying devices (2) included in the arrangement and present on the greenhouse roof are adapted to spray water over the roof (13) of a multi- ridge, so-called block greenhouse.

4. An arrangement as set forth in claim 1, characterized in that there is further provided a heat pump assembly for the refrigeration of cooling water used in the arrangement or for the recovery of heat.

5. A method for the refrigeration of cooling water intended for dehumidifying and cooling greenhouse air, characterized in that, in the method, warmed- up cooling water, which has been used for the dehumidifying and cooling of greenhouse air, is conveyed up onto a roof (6; 13) of the greenhouse and refrigerated by spraying it over an external surface of the roof, and also water, which has been refrigerated by spraying, is recovered for reusing it for dehumidifying and cooling the indoor air of the greenhouse.

6. A method as set forth in claim 5, characterized in that, in the method, water to be refrigerated is sprayed on the greenhouse roof (6) in upward direction towards a ridge of the greenhouse or in downward direction from a ridge of the greenhouse over one or two sloping surfaces.

7. A method as set forth in claim 5, characterized in that, in the method, water to be refrigerated is sprayed over the roof (13) of a multi-ridge, so- called block greenhouse.

8. A method as set forth in claim 5, characterized in that, in the method, at least some of the water, which has been sprayed over the greenhouse roof (6; 13) and recovered therefrom by means of collection devices located on the greenhouse roof (6; 13) or in its vicinity, is conveyed gravitationally to air cooling and dehumidifying equipment (8) present inside the greenhouse.

9. A method as set forth in claim 5, characterized in that, in the method, at least some of the water, which has been sprayed over the greenhouse roof

(6; 13) and recovered therefrom by means of collection devices located on the greenhouse roof (6; 13) or in its vicinity, is sprayed downward by means of nozzles (9) provided on the collection devices (3).

10. A method as set forth in claim 5, characterized in that, in the method, the cooling water to be used in the system is further refrigerated by means of a heat pump assembly.

11. A greenhouse, which is equipped with devices enabling the greenhouse air to be cooled and dehumidified by means of water, said greenhouse further comprising devices (1) by means of which the warmed-up cooling water, which has been used for drying and cooling the greenhouse indoor air, can be conveyed up onto a roof (6; 13) of the greenhouse, and devices (2) for spraying water over an external surface of the roof (6; 13), as well as collection devices (3) which enable the water, which has been refrigerated by means of spraying, to be circulated for reusing it in dehumidifying and cooling equipment present inside the greenhouse, characterized in that the collection devices (13) for water sprayed over the greenhouse roof are provided on the roof or in the vicinity of the roof so as to enable at least some of the water sprayed over and recovered from the roof to be conveyed directly to cooling equipment present inside the greenhouse and/or that the water collection devices (3) present on the greenhouse roof are fitted with nozzles (9) for spraying the cooling water further downward.

12. A greenhouse as set forth in claim 11, characterized in that the devices (2) spraying water over the roof (6) are adapted to spray water in upward direction towards a ridge of the greenhouse and/or from a ridge of the greenhouse in downward direction over one or two sloping surfaces.

13. A greenhouse as set forth in claim 11, characterized in that the devices (2) spraying water over the roof are adapted to spray water over a roof (13) of a multi-ridge, so-called block greenhouse.

14. A greenhouse as set forth in claim 11, characterized in that it is further fitted with a heat pump assembly for the further refrigeration of water used for cooling the greenhouse, or for the utilization of heat.