WO2017021584A1

WO2017021584A1 - Method and apparatus for drying and cooling air

Info

Publication number: WO2017021584A1
Application number: PCT/FI2016/000020
Authority: WO
Inventors: Orvo Backman; Kari KANTOLUOTO; Pentti RYTKÖNEN
Original assignee: Kylmäveräjä Oy
Priority date: 2015-08-03
Filing date: 2016-08-03
Publication date: 2017-02-09
Also published as: FI20180031L

Abstract

A method for cooling and/or drying a space equipped with an air dryer (4) and an air cooling apparatus (11), according to which method the regeneration air of the air dryer is heated using the energy attained from the inlet air cooling radiator (11). The heating energy required by the regeneration air heating radiator (13, 15) is taken with a heat pump from the inlet air cooling radiator and from the cooling radiator (16) of the hot exhaust air used for regeneration. The apparatus has a heat pump belonging to the cooling apparatus, which heat pump includes a compressor (12), an inlet air cooling radiator (11 ) and an outside condenser (14) and that the regeneration air heating radiator of the drying apparatus' rotor is connected to the condensing circuit of the heat pump.

Description

METHOD AND APPARATUS FOR DRYING AND COOLING AIR

OBJECT OF THE INVENTION The object of the invention is a method according to the introduction of claim 1 for drying and cooling air. The object of the invention is also a method for heating the regeneration air in air drying and a method for arranging the air-conditioning of a room such that cooled air can be directed into the room energy-efficiently without moisture condensing in the equipment.

PRIOR ART

The cooling of air entering a room or other space through air-conditioning is often necessary during warm seasons. In known air-conditioning equipment, cooling radiators are usually used in which the moisture contained in the air condenses into water, which is removed into a sewer. Most typically the cooling of the air is carried out such that water is not removed from the process at all, instead the cooled air, which has a relative humidity percentage of approximately 98%-100%, is blown into the room just as it is. This leads to structures becoming damp, problems with indoor air and mould growth in structures. In the summer, the air is very moist and warm air contains a lot of water, which means that there is a lot of water that will condense. A major problem in this case is that the cooling radiators function in conditions that are close to the dew point, as a result of which the cooling radiator, condense water tank, droplet separator and parts of the channel are constantly wet during the cooling process. This easily leads to the equipment and air channels developing mould, which can be extremely harmful to the health of people in the room and to any food in the space.

In order to avoid the above-mentioned harmful consequences caused by moisture, a dry refrigeration method can be used in which the moist inlet air is dried sufficiently before being directed to the cooling radiator. In this case no water condenses in the cooling radiators, which eliminates any problems caused by moisture in the air-conditioning equipment and the room or any other air-conditioned space. Usually, adsorption dryers with a spinning rotor through whose cells the air to be dried is directed are used for drying the air. In the dryer, the moist air is directed through one sector of the rotor in which case at least some of the moisture in the air binds to the rotor. In order for the adsorption dryer to function continuously, its rotor must be regenerated, i.e. the moisture bound to the rotor must be removed before the rotor will again be able to bind moisture from the air to be dried. Regeneration takes place such that the rotor is spun to another position, in which position a hot airflow is directed through the rotor. In this case the moisture in the rotor's cells transfers to the hot air directed through the cells and the moisture exits the rotor along with the hot air. After this, the rotor again spins into a position in which moist air to be dried can be directed through it.

Known adsorption dryers are efficient and reliable. Heating the regeneration air to be directed through the dryer's rotor requires a lot of energy, however. The dryer usually has an electric radiator for heating the regeneration air. In order to achieve significant drying efficiency, a large amount of electrical power must be used which limits the use of the dryer. For this reason drying is often not carried out at all in practice. PURPOSE OF THE INVENTION

The purpose of the invention is to achieve a more advantageous and efficient method for drying and cooling air. The purpose of the invention is also a method and apparatus for the heating of regeneration air in air drying. Furthermore, the purpose of the invention is to achieve more efficient control of the humidity of a room's inlet air. By means of the invention, the humidity of the inlet air can be controlled and adjusted efficiently using a dry refrigeration heat pump without the moisture in the air condensing on the air-conditioning equipment or regeneration equipment. By means of the invention, the air to be directed into the space can be dried and/or, optionally, cooled according to need.

The purpose of this invention is to achieve a more advantageous and overall cost-efficient air-conditioning drying method and air-conditioner and control of a room's humidity without the moisture in the air condensing on the equipment. According to the invention, heat attained from the air-conditioning equipment in connection with cooling is used to heat the regeneration air of the dryer's rotor required for drying the air. According to the invention, in order to improve the overall cost-effectiveness of the equipment, the electric radiator used to heat the regeneration air of the rotor spinning in the adsorption dryer is replaced either partly or fully with one or more heat pumps. By means of the equipment according to the invention, the air to be directed into the space can be dried and/or, optionally, cooled according to need. According to the invention, the heating energy required by the heating radiator for the regeneration air of the dryer used to dry the air is taken from a part of the air-conditioning equipment where the heat usually goes to waste. In this case, hygienic moisture control can be achieved energy-efficiently using dry refrigeration such that the equipment would only require a third of the electrical energy otherwise required.

More advantageously, energy-efficiency is achieved by heat being transferred for the heating of the drying apparatus' rotor using a heat pump from a part of the air-conditioning equipment in which heat usually goes to waste or from a channel of the air-conditioning equipment through which air and heat is removed into the outside air. Such parts of air- conditioning equipment are, for example, the inlet air cooling radiator, cooling radiator for hot exhaust air used for regeneration of the drying apparatus' rotor and other exhaust air cooling radiator.

The overall cost-effectiveness of the drying of the air-conditioning equipment is

substantially impacted by the utilisation of the heat attained from the inlet air cooling radiator and/or the hot exhaust air used in the regeneration of the drying apparatus' rotor. According to the invention, the heat energy attained from the inlet air cooling radiator and/or the heat energy of the hot exhaust air for the regeneration of the drying apparatus' rotor can be transferred to the heating of the air required for regeneration of the drying apparatus' rotor using one or more heat pumps.

According to the invention, a heat pump can be used in the equipment for transferring heat, the compressor of which transfers the heat energy of a radiator, such as the air- conditioning's inlet air cooling radiator, and the energy taken by the compressor to a heating radiator, such as a heating radiator required for regeneration of the drying apparatus' rotor. According to the invention, the heating pump's compressor can also transfer the energy of the exhaust air cooling radiator used for regeneration of the drying apparatus' rotor and the energy taken by the compressor to the heating radiator required for regeneration of the drying apparatus' rotor. If both of the above-mentioned heat energies are used for heating the air required to regenerate the drying apparatus' rotor, two separate heat pumps can be used, according to the invention, for transferring the heat. In this case also two compressors, two cooling radiators and two heating radiators can be used to heat the air required to regenerate the drying apparatus' rotor.

The advantage of the regeneration air heating method according to the invention is that the heat pump function can be used to cool air and for the cooling of the high-energy regeneration exhaust air for the energy needs of the heating radiator. The heating radiator can be of a direct condensation type or operate through a liquid.

The heat pump function can be used efficiently to cool air and to pre-heat the regeneration air and cool the high-energy regeneration exhaust air and post-heat the regeneration air.

The advantage of the method according to the invention is also that if drying is not required but the interior space is too hot, the same equipment can be used to cool the inlet air as much as is required. In this case the heat pump transfers energy from the inlet air to the outside air. What is essential here is for the equipment to include an efficient outside air condenser. The heat pump's compressor and outside air condenser can be designed with the required power regardless of the drying apparatus.

Also an existing air-conditioning system using a condensing cooling radiator can be converted into a hygienic dry refrigeration system such that an adsorption dryer is added to the equipment to dry the air to be cooled before it is cooled.

Also an existing air-conditioning system that has a cooling radiator using uncondensed supply air that has a relative moisture level of 98%-100% can be converted into a hygienic dry refrigeration system such that an adsorption dryer is added to the equipment which dries the air to be cooled before it is cooled. This allows the entire capacity of the cooling radiator to be utilised. Otherwise the cooling must be limited when the dew point is reached and the equipment releases water and the moisture level indoors is such that the structures become damp and grow mould.

According to the invention, the heat pump's evaporating radiator is connected to the adsorption dryer's rotor's regeneration exhaust air channel and the heat pump's condensing radiator is connected to the regeneration air channel leading to the dryer's rotor. Using the heat pump, heat energy from the regeneration exhaust air can be advantageously transferred for heating the regeneration air. In known equipment heat energy from the regeneration exhaust air is wasted when it exits into the outside air.

When changing the existing equipment, also the existing inlet air cooling radiator can be changed into the heat pump's evaporating radiator. The heat pump's condensing radiator is connected to the exhaust air channel of the drying apparatus' rotor in which case the heat energy extracted from the air in cooling the inlet air can be transferred to heating the drying apparatus' rotor's regeneration air. The inlet air cooling radiator can also be left in place and connected, through a heat exchanger, to an evaporator circuit of the heat pump whose condensing radiator heats the air flowing to the drying apparatus' rotor. If needed, a transfer pump can also be used to transfer energy to the heat exchanger. The cooling radiator can be converted into the heat pump's evaporating radiator, even though the investment costs will rise, because this results in a more efficient heat transfer solution.

The electric radiator in the regeneration air channel of the air dryer's rotor can be removed and replaced entirely by a condensing radiator with one or more heat pumps as presented above. However, the electric radiator can be left in place so that one or more of the available heating radiators is used to heat the dryer's rotor's regeneration air in accordance with what is the most advantageous in terms of overall cost-efficiency. According to the invention, the equipment can, in order to reduce investment costs, be dimensioned for example such that, in addition to an electric radiator, one or more low- power heat pumps for heating the regeneration air of the dryer's rotor are installed. By dimensioning the heat pumps, the amount of energy recovered using the heat pumps and the volume of air flowing to the drying apparatus' rotor that has to be heated using the heating radiator can be adjusted. In practice, the regeneration air flowing to the drying apparatus' rotor can be heated with heat pumps, but if peak power is required, also the existing electric radiator can be used for heating. The electrical power requirement and energy consumption of the electric radiator can thus be reduced significantly. According to the invention, the optimal energy consumption situation is, however, achieved when the electric radiator can be left out and all of the heat required for heating the drying apparatus' rotor is transferred using one or more heat pumps from parts of the equipment where heat is normally wasted. Particularly new equipment to be installed is worth making more efficient and advantageous such that the air-conditioning's cooling radiator is replaced with the heat pump's evaporating radiator.

According to the invention, the cooling and drying of the air can be combined such that the cooling radiator's power is used for heating the dryer's regeneration air. The power of the cooling radiator can be used either entirely or in part for heating the regeneration air's heating radiator. If the need for cooling is considerable, the cooling radiator's power is also so large that just a portion of it is enough to heat the regeneration air's heating radiator. The remainder of the energy is channelled out by making the external condensing radiator large enough. In a situation such as this, drying does not result in the need for any additional energy. In practice, the overall power requirement may even decline considerably as the dry refrigeration according to the invention does away completely with the need to heat the inlet air, which is essential in known methods.

If, on the other hand, the need for cooling is not large, the combined cooling and drying equipment is adjusted according to the regeneration heat energy requirement of the dryer. However, in both cases the increase in operating costs caused by the dryer remains low because the need for air drying is estimated to be just approximately 2,000 h/a. In any case, the benefit resulting from drying is so large that it should never be left out of investment plans. A relatively small level of drying of the air prevents the formation of mould growth in structures. The current practice in which moist air, and with it large amounts of water, is taken into buildings is harmful as is proven by many mould-infested schools and office buildings that are unfit for use.

EXAMPLES OF EMBODIMENTS

In the following, the invention is described by an example with reference to the accompanying drawings, in which

Figure 1 shows a schematic view of an apparatus according to the invention for the optimisation of a dryer's regeneration.

Figure 2 shows a schematic view of the apparatus in Figure 1 connected to an air- conditioning system.

Figure 3 shows a schematic view of a solution for the apparatus in Figure 1.

Figure 4 shows a schematic view of a cooling solution according to prior art.

Figure 5 shows a schematic view of another cooling solution according to prior art.

Figure 6 shows a schematic view of a cooling solution according to the invention.

Figure 7 shows a schematic view of another solution according to the invention.

Figure 8 shows a comparison of process diagrams.

Figure 9 shows a schematic view of a freezing space's equipment arrangement.

Figure 10 shows a detail of the freezing space in Figure 9.

Figure 11 shows a schematic view of a unit according to the invention that can optionally be used for the cooling and/or drying of air.

Figure 12 shows a side view of a cooling and/or drying unit according to the invention.

DESCRIPTION OF THE FIGURES Figure 1 shows a dryer 4 linked to the air-conditioning equipment into whose air channel 20 the inlet air 7 is directed using a fan 10. The moist inlet air 7 is directed through the dryer 4 causing a portion of the moisture contained in the air to bind to the rotor cells of the dryer 4. When directed through the dryer 4 the air warms up due to which the dried air must be cooled before the air 18 exits into the room or other space to be air-conditioned.

The regeneration of the air dryer 4 is arranged such that the regeneration air 1 is directed to the regeneration air channel 21 through the air filter 2 using a fan 5. The regeneration air can be taken from the outside air or from a suitable section of the air-conditioning equipment or other space. The regeneration air is heated and directed through the cells of the dryer 4 in which case the warm air regenerates the cells, removing the moisture bound to them. The moist regeneration exhaust air 6 exits into the outside air. After this, moist air can once again be directed through the regenerated cells of the dryer 4 in order to dry it.

The heating of the regeneration air of the air dryer 4 is arranged such that a first heat pump is used to pre-heat the regeneration air. Hence the heat is transferred from the warm air flowing in the air channel 20, directed through the dryer 4, to the regeneration air flowing in the regeneration air channel 21. The first heat pump equipment carrying out the pre-heating includes a cooling radiator 11 located in the air channel 20, compressor 12, regeneration air pre-heating radiator 13 and a condensing radiator 14. The inlet air cooling radiator 11 is the evaporating radiator for the first set of heat pump equipment and the regeneration air pre-heating radiator 13 is the condensing radiator for the first set of heat pump equipment. The other condensing radiator 14 of the heat pump equipment is located outside in the outside air.

When pre-heating the regeneration air, the heating energy of the pre-heating radiator 13 is taken from the cooling radiator 11. In this case the compressor 12 transfers the cooling radiator's heat energy and the compressor's electrical energy to the pre-heating radiator 13 and the outside condenser 14. The pre-heating radiator 13 and outside condenser 14 are connected in series.

The post-heating of the heating of the regeneration air of the air dryer 4 can also be arranged using another heat pump such that heat is transferred from the hot regeneration air directed through and exiting from the dryer 4 back to the regeneration air directed to dryer 4. The post-heating heat pump equipment includes the exiting regeneration air's cooling radiator 16, compressor 17 and post-heating radiator 15. The cooling radiator 16 of the regeneration exhaust air 6 is the evaporating radiator for the second set of heat pump equipment and the post-heating radiator 15 for the regeneration air is the condensing radiator for the second set of heat pump equipment. In the post-heating of the regeneration air the energy required by the post-heating radiator 15 for the regeneration air is taken from the cooling radiator 16. The compressor 17 of the heat pump transfers the cooling radiator's heat energy and the compressor's electrical energy to the post-heating radiator 15. Figure 2 shows a schematic view of the air dryer 4 in Figure 1 and its heat pump equipment connected to the air-conditioning system of a larger space 22. In the example shown in Figure 2 the space 22 is air-heated. The heating can also be arranged in some other way in which case the equipment presented in Figure 2, for example, is connected to the air-conditioning. Air is circulated in the equipment using a fan 10 through the circulation air channel 19 and air channel 20. During the heating season, the circulated air is heated using the heating radiator 3 in the air channel 20, which heating radiator is a heat recovery ventilator (HRV) or some other external source of heat. In addition the air 18 conducted into the space 22 can be heated using a heating radiator 9, which is, for example, a waste heat recovery radiator. The heating radiator 9 can be heated, in a known manner, for example with electricity or district heat or it is, for example, a condensate heat recovery radiator. Some of the air in the space 22 is exhaust air 25, which is conducted out, for example, through sanitary facilities and the exhaust air channel 24 using an exhaust air fan 23. The required make-up air, i.e. inlet air 7 is taken from the outside air. Outside the heating season, such as in summer, the space 22 does not need to be heated. Instead it requires cooling, which is taken care of using the cooling radiator 11 in the air channel 20. In summer, the outside air contains plenty of moisture so that the inlet air is extremely moist and the air 18 conducted into the room must be dried first. According to the invention, the air 18 conducted into the room is dried with a dryer 4 and cooled using a cooling radiator 1 1 that is, at the same time, according to the invention, the evaporating radiator of the first heat pump.

In the summer, the volumetric flow rate of the air 18 conducted into a large room is large, so a considerable amount of heat can be transferred from this volume of air for pre-heating the regeneration air 1 of the dryer 4. The heat transfer is carried out as presented in Figure 1 so that the cooling radiator 11 in the air channel 20 is simultaneously the evaporating radiator of the first heat pump. The condensing radiator of the heat pump is the pre-heating radiator 13 in the regeneration air channel 21 of the dryer 4. The regeneration air 1 can be taken from the outside air which is warm in summer but, if needed, it can also be taken from elsewhere in the air-conditioning system or another space. The post-heating of the regeneration air 1 is carried out in the same way as presented in Figure 1 such that the heat from the hot regeneration exhaust air 6 directed through the rotor of the dryer 4 is transferred back to the regeneration air 1 conducted to the rotor using a second heat pump. In this case, a cooling radiator 16 is located on the side of the rotor's exhaust air 6 in the regeneration air channel 21 , which is the evaporating radiator of the second heat pump. A second heating radiator in the air channel 21 leading to the rotor, i.e. the post-heating radiator 15 for the regeneration air is the condensing radiator for the second heat pump.

The advantage of the method and apparatus according to the invention is its overall cost- effectiveness because the regeneration air 1 of the drying apparatus 4 can be heated cost- effectively and efficiently by using one or two heat pumps.

Two heat pumps are used in Figure 1. In this case the inlet air 7 for the air-conditioning is dried using the dryer 4 and cooled using the cooling radiator 11 , which is the evaporating radiator of the first heat pump. In this case the cooling of the air 18 conducted into the room can be carried out advantageously without moisture problems because the air dried with the dryer 4 does not condense on the cooling radiator 11. At the same time, the heat contained in the inlet air 7 can be transferred to the pre-heating radiator 13 for the regeneration air 1 , which is the condensing radiator of the first heat pump.

In this solution, also heat energy is recovered from the hot regeneration air conducted through the dryer 4 using the cooling radiator 16, which is the evaporating radiator of the second heat pump. The heat is transferred to the post-heating radiator 15 for the regeneration air, which is the condensing radiator of the second heat pump. Thus as much heat energy as possible can be recovered from the regeneration exhaust air 6 of the dryer 4 passing into the outside air and transferred to heating the regeneration air 1 going to the rotor.

The post-heating of the heating of the regeneration air of the air dryer 4 has been arranged using another heat pump such that heat is transferred from the hot regeneration air directed through and exiting from the dryer 4 back to the regeneration air directed to the dryer 4. The post-heating heat pump equipment includes the exiting regeneration air's cooling radiator 16, compressor 17 and post-heating radiator 15. The cooling radiator 16 of the regeneration exhaust air 6 is the evaporating radiator for the second set of heat pump equipment and the post-heating radiator 15 for the regeneration air is the condensing radiator for the second set of heat pump equipment.

Figure 3 shows a solution according to the invention in which a known air-conditioning system is converted into an air-conditioning system equipped with a dryer 4. The air to be dried going to the dryer 4 is taken through a channel 29 and the volume of air flow to be dried is adjusted using a fan 30.

The dryer 4 is an adsorption dryer whose rotor's regeneration exhaust air 6 channel has been connected to the evaporating radiator 16 of the heat pump. The heat pump's condensing radiator 15 has been connected to the regeneration air channel 21 leading to the rotor of the dryer 4, in which case heat energy can be transferred from the

regeneration exhaust air to heating the regeneration air.

In Figure 3 the inlet air cooling radiator 11 present in the air-conditioning equipment has been left in place and it has been connected via the heat exchanger 28 to the vaporising circuit of the heat pump so that the compressor 12 transfers the heat energy of the cooling radiator 11 to the condensing radiator 13 of the heat pump, which heats the air going to the rotor of the drying apparatus 4.

In Figure 3, there is also an electric radiator 31 in the regeneration channel 21 in which case any of the heating radiators 13, 14 and 31 in the channel 21 can optionally be used for the heating of the regeneration air of the dryer 4. The heating of the regeneration air is achieved through heat pumps but the electric radiator 31 can be used to assist if necessary.

A comparison is shown in Figures 4, 5 and 6 in which the electrical energy consumption of the known cooling solutions presented in Figures 4 and 5 are compared to the electrical energy consumption of the cooling solution according to the invention presented in Figure 6. The same cooling power is achieved using all of the compared solutions, but in different ways. A known cooling solution is used in Figures 4 and 5 in which the air to be cooled is not separately dried, instead when the air is cooled the moisture in it condenses into water. In this case the cooling radiator and air channels are constantly wet, which leads to a clear risk of mould forming on the equipment. In the dry refrigeration solution according to the invention presented in Figure 6 the air is instead dried before it is cooled in which case water does not condense on any part of the equipment and there is thus no risk of mould forming.

In all of the examples in Figures 4, 5 and 6, the temperature of the outside air is 25 °C and its relative humidity is 60%, which corresponds to the conditions on a normal summer's day. In this case there is approximately 12 g of water/kg of air. In all of the examples in Figures 4, 5 and 6, the temperature of the space 22 to be cooled is 21 °C. In all of the examples there is additionally the same situation in which 3,000 kg/h of products are brought into the room, which have to be cooled from a temperature of 80 °C to a room temperature of approximately 20 °C. The heat energy released by the products is thus 170 kWh and the amount of water released is 45 kg/h. As these products warm up the space 22 to be cooled, the temperature of the exhaust air is 33 °C and the relative humidity 32%. This air can be circulated at least partly through the cooling radiator 11 back into the space 22 to be cooled as is presented below.

Figure 4 shows a schematic view of a cooling solution according to prior art, in which air taken from the outside air, coming inside, is cooled using a conventional cooling radiator 11. The air conducted through the cooling radiator thus cools and the moisture in the air condenses as water, which exits into a sewer. When the air is cooled in the cooling radiator from a temperature of 25 °C to the dew point, which is around 17 °C, and from there down to a temperature of about 12 °C, 94 kg/h of water is removed from the air into the sewer. The required volume of air, 6 m³/s, is cooled using a heat pump, whose compressor 12 requires an electric power of 72 kW and the cooling capacity of the heat pump is 165 kW. The air cooled to a temperature of 12 °C has 8 g of water/kg of air remaining and its relative humidity is approximately 95%. Before the cooled air can be channelled into the room it must be heated. A heating radiator 9, which has a power of 19 kW, is required for heating the air to a temperature of about 15 °C.

The electrical power required in the solution in Figure 4 is usually close to 100 kW when also including the capacity of the electrical motors of the inlet fan 10 and exhaust air fan 32. In some solutions the capacity, 19 kW, of the heating radiator 9 can, however, be attained from a heating boiler, for example, in which case the total electrical power required is reduced in terms of this. It is, however, disadvantageous in terms of the power consumption that the capacity must first be used for cooling the air and then again for heating the air. Figure 5 shows a schematic view of another cooling solution according to prior art, which corresponds for the most part with what is presented in Figure 4. The difference in the solution in Figure 5 is that the air exiting the space 22 to be cooled is recycled through the cooling radiator 11 back into the space 22 to be cooled. The temperature of the air exiting the space 22 to be cooled is 33 °C and the relative humidity is 32%. It thus contains approximately 10.3 g of water/kg of air, i.e. less than in the air brought in from outside. Due to the higher temperature, the required capacity of the cooling radiator is 184 kW. The recycled air is cooled to the dew point, which, in this case, is about 15 °C and from there down to a temperature of approximately 12 °C, causing about 46 kg/h of water to be removed from the air into the sewer.

Similarly to Figure 4, in the solution in Figure 5, a heat pump whose compressor 2 has a required electrical power of 72 kW is used to cool a volume of air, 6 m³/s. The air must be warmed up before it can be channelled into a room. A heating radiator 9, which has a power of 19 kW, is required for heating the air to a temperature of about 15 °C. The electrical power, less than 100 kW, required by the solution in Figure 5 that does not contain an exhaust air pump is slightly less than in Figure 4.

Figure 6 shows a schematic view of a cooling solution according to the invention in which air is first dried and only then cooled. In this case, similar problems do not arise as with known solutions in which the water in the cooling radiator easily causes mould problems. The solution in Figure 6 is a closed process in which, as in the examples in Figures 4 and 5, the temperature of the space 22 to be cooled is 21 °C and 3,000 kg/h of products are brought in which need to be cooled from a temperature of 80 °C to a room temperature of about 20 °C. The heat energy released by the products is thus 170 kWh and the amount of water released is 45 kg/h, in which case the products heat the space 22 to be cooled so that the temperature of the exhaust air rises 33 °C and the relative humidity 32%. In this case the air contains approximately 10.3 g of water/kg of air. In the solution in Figure 6 at least a portion of the air exiting the space 22 to be cooled is dried and cooled after which the air is circulated back to the space 22 to be cooled. The circulation air flow achieved by the inlet air pump 10 is 6 m³/s. In the example presented in Figure 6, the air exiting the space 22 to be cooled is divided into two portions so that the first air flow, which is circulated through the dryer 4, is directed into the first air channel 34 at 3.6 m³/s. After the dryer, the relative humidity of the air is 13% and the temperature is 43 °C, in which case the air contains approximately 7 g of water/kg of air. The second portion of the air flow exiting the space 22 to be cooled at 2.4 m³/s is directed into another air channel 35 after which the air is mixed with the first air flow entering through the dryer 4. The relative humidity of the mixed 6 m³/s air flow is 19% and the temperature is 39 °C, in which case it contains approximately 8 g of water/kg of air. The air dried in this manner is then channelled into a cooling radiator 11 in which the temperature falls to approx. 15 °C. Because the air flow channelled into the space 22 to be cooled contains only 8 g of water/kg of air, its relative humidity only rises to the value 80% at a temperature of 15 °C, so at no point in the process is there a danger of the moisture in the air condensing into water.

In the example in Figure 6, the electrical power required by the heat pump's compressor 12 is also 72 kW as in the examples of Figures 4 and 5. However, the 19 kW heating radiator 9 presented in Figures 4 and 5 is not needed at all. The example in Figure 6, however, contains the hot regeneration air directed to the dryer 4. The problem in known solutions has been that the heating of the regeneration air of the dryer 4 has consumed a lot of expensive energy.

According to the invention, the heating of the regeneration air of the dryer 4 in Figure 6 is carried out using the same heat pump and compressor 12 that are used for cooling the cooling radiator 11. What is essential here is for the equipment to have an efficient condenser in the outside air, i.e. a condensing radiator 14 in which case the size and power of the condenser do not limit the power to be gained from the heat pump. As the temperature of the regeneration air of the dryer 4 must be at least 82 °C it is also essential that the equipment utilises high-temperature refrigerants such as C0₂ or ammonia. The condensing temperature of these is, for example, 115 °C in which case the temperature of the regeneration air of the dryer 4, 82 °C, can be reached.

In Figure 6 the regeneration air of the dryer 4 is heated using condensers connected to the circuit of the heat pump and compressor 12, which condensers are the regeneration air pre-heating radiator 13 and the regeneration air post-heating radiator, i.e. superheat radiator 15. The ratio of refrigerant conducted to the condensers 13 and 15 can be adjusted using a valve 36. After the condensers 13 and 15 the refrigerant is conducted to an efficient outside condenser 14, i.e. the condenser in the outside air. Using the efficient outside air condenser 14, the capacity of the equipment can be increased to the required level without the restrictions exhibited in the closed circuits according to prior art. According to the example in Figure 6, the regeneration air of the dryer 4 is taken from the outside air whose temperature is 25 °C and relative humidity 60%. In the first heating radiator 13 the air heats to a temperature of 71 °C and in the second heating radiator 15 the air heats up to the temperature required for regeneration, some 80 °C, in which case the relative humidity of the regeneration air conducted into the dryer is approximately 4%. The part of the rotor of the dryer 4 that has been regenerated in such manner then spins to a position in which it dries the air entering the room 22.

In accordance with the cooling process, the refrigerant in the cold accumulator or expansion valve 37 of the heat pump converts into a gas and cools down in the evaporator, i.e. cold heat exchangers. The heat pump in Figure 6 has two evaporators that are the air-conditioning inlet air's cold radiator 11 and the cooling radiator 16 of the regeneration air exiting the dryer. Valves 38 and 39 can be used to adjust the access of the refrigerant to the cold radiator 11 of the air-conditioning's inlet air and to the cooling radiator 16 for the regeneration air exiting the dryer. In this case it is possible to adjust whether the refrigerant flows freely to both cooling radiators 11 and 16 or in which ratio the refrigerant is divided up between them. An adjustment can also be made in which the refrigerant only goes to the other cooling radiator, which solution option is described below in more detail.

What is essential about the example in Figure 6 is that although the traditional cooling equipment based on the condensing of water in Figures 4 and 5 have been replaced with a considerably better solution based on dry refrigeration, the consumption of electrical energy by the entire equipment is mostly the same or even lower than in known equipment. According to the invention, the hot regeneration air required by the dryer 4 is achieved using a heat pump which includes a cold radiator 11 for the air-conditioning's inlet air, regeneration air heating radiators 13 and 15, a regeneration air cooling radiator 16 and an efficient condensing radiator 14 in the outside air, which are connected to the same circuit as the compressor 12. The condensing radiator 14 in the outside air is essential because the air-conditioning's cooling simultaneously defines the removal of moisture. In known solutions cooling cannot be carried out more than the air condenses in the condenser.

Figure 7 shows an example of an air-conditioning solution according to the invention that is suitable to many kinds of public spaces such as offices and schools. It is suitable to be connected to a space that already uses geothermal heat. The equipment can also be built to be mobile in which case it can be taken as needed to the required location either permanently or temporarily. What is essential about the equipment is that it has three separate air flows, which are the drying and/or cooling air flow to the room 22, the hot regeneration air air flow through the rotor of the dryer 4 and the air flow conducted through the outside condenser.

The equipment shown in Figure 7 includes both a drying apparatus 4 and a cooling radiator 11 with which the air channelled into the room 22 can be dried and/or cooled. The drying apparatus 4 and the cooling radiator 11 are connected to the circuit of the heat pump's compressor 12 in which case the ratio between drying and cooling can be adjusted as required. If the outside air and also the inside air are very moist, the equipment can be adjusted to mainly dry. If, on the other hand, the air is sufficiently dry the equipment can be adjusted to only cool. What is essential is that the equipment includes an effective condenser 14 in the outside air in which case the heat pump can be made to function as effectively as possible in drying and/or cooling the air channelled into the room 22. What is outstanding about the equipment in accordance with the invention in Figure 7 is that the equipment can be adjusted as needed for drying and/or cooling in the required ratio.

The excellent compatibility of the equipment with different buildings is based on the effective air drying in the solution example in Figure 7 but it still does not require the high- power electrical radiators used in known solutions for heating the regeneration air of the dryer 4. The heat of the regeneration air is recovered using a heat pump from the cooling radiator 11 of the air-conditioning and from the cooling radiator 16 of the exiting regeneration air and transferred to the regeneration air heating radiators 13 and 15. When high-temperature refrigerant is used in the circuit of the heat pump's compressor 12 as a refrigerant, such as C0₂ or ammonia, the temperature, 82 °C, of the regeneration air required by the rotor of the dryer 4 can be achieved advantageously.

The equipment in Figure 7 includes an inlet air channel 20 through which air is conducted into the room 22, an exhaust air channel 41 and a circulation air channel 34. The equipment can also include a heat recovery apparatus 40, but this is not necessary. In Figure 7 where the air is taken from the outside air the temperature of which is 25 °C and with a relative humidity of 60%, in which case the air contains 12 g of water/kg of air. This is a common situation on a normal summer's day. The drying of this kind of air is essential because if air of this type is cooled, the dew point is already at a temperature of 17 °C, in which case the moisture in the air condenses as water. In Figure 7, outside air is conducted through the channel 44 through the rotor of the dryer 4, causing the air to dry such that its relative humidity is 8% and temperature some 49 °C. In this case the air contains just 5 g of water/kg of air, whereby the air can be cooled to a temperature of 20 °C without moisture problems.

In Figure 7 air that is 20 °C warm and with a relative humidity of 40% is channelled into the room 22 such that a portion of the air exiting the room 22 is recycled. As the temperature and humidity of the air exiting the room 22 increase somewhat, an advantageous mixing ratio is achieved by adjusting the valves 42 and 43. This makes it possible to adjust how much air is recycled and mixed into the air coming from outside and how much the air with the desired mixing ratio needs to be dried or cooled. Air with a temperature of 20 °C and a relative humidity of 40% is brought into the room 22 in which case it contains less than 6 g of water/kg of air. This type of air is extremely advantageous when the aim is to avoid the formation of problems caused by moisture.

The circuit of the compressor 12 in the heat pump in Figure 7 is mainly identical to the one in Figure 6. An essential difference is, however, that at least one chilled beam 45 has been added to the room 22 in Figure 7, which beam is connected to the circuit of the compressor 12 and operates similarly to the cold radiator 11. The cooling effect of the chilled beam 45 on the room 22 can be increased with the fan 46 connected in connection with the chilled beam 45. The chilled beams 45 are extremely well suited to be placed in connection with the equipment according to the invention presented in Figure 7 because the temperature of the air in the room 22 is 20 °C and the relative humidity 40%. This type of air contains less than 6 g of water/kg of air and its dew point is at a temperature of approximately 6 °C. The chilled beams 45 are thus made extremely effective because they can be cooled to a temperature of, for example, 8 °C without moisture problems.

Chilled beams are used in solutions according to prior art such that they are the only cooling equipment in the room. This has led to failures due to the excessive amount of humidity in the room's air. The air mentioned in the previous example, which has a temperature of 25 °C and a relative humidity of 60%, is not possible to cool using a chilled beam because the dew point of this type of air is already at a temperature of 17 °C. In this case the automation of the equipment prevents the cooling of the chilled beam below a temperature of 20 °C because otherwise the water condensing on the surface of the chilled beams would drip on the people in the room 22. It is clear that, in this case, the cooling power of the chilled beams at a temperature of some 20 °C is low. The equipment in Figure 7 can be adjusted as required to both cool and dry the air or to just cool or dry it. If the equipment is only used for cooling, the valves leading to the rotor of the dryer 4 are closed. If the equipment is only required for use in drying, for example, at night when there are no people on the premises, the inlet air valve 26 for the outside air and the exhaust air valve 33 are closed. Thereafter the air only circulates through the dryer 4.

Figure 8 presents a Mollier diagram, which compares the operations of a known condensation cooling process and a drying-cooling process according to the invention. Cooling in known apparatuses is carried out by condensing the moisture in the air into water. In the process according to the invention, air is dried before cooling, in which case no condensed water is created at any point.

The diagram in Figure 8 shows three vertical lines and the lines connecting them. At the top of the right-hand vertical line is the situation presented in Figure 4 in which the outside air temperature is 25 °C, the relative humidity is 60% and the air contains 12 g of water/kg of air. According to a known condensation-cooling process, air is cooled using a cooling radiator such that its temperature falls to the dew point, which, in this case, is 17 °C at the bottom of the right-hand vertical line. The moisture in the air thus begins to condense into water on the surface of the cooling radiator. When the temperature has fallen to the value 11 °C at the bottom of the left-hand vertical line, more water has left the air and the air contains just 8 g of water/kg of air. After this the air must be heated to a temperature of 15 °C, i.e. slightly upward along the left-hand vertical line in the diagram. The middle vertical line shows the circulation air situation in Figure 5 in which case the temperature of the air exiting the space 22 to be cooled is 33 °C and the relative humidity 32%, in which case the air contains some 10.3 g of water/kg of air. This air is also cooled using a condensation-cooling radiator such that its temperature falls to the dew point, which, in this case, is 15 °C at the bottom of the right-hand vertical line. Moisture in the air begins to condense into water on the surface of the cooling radiator and when the temperature has fallen to the value 11 °C at the bottom of the left-hand vertical line, more water has left the air and the air contains just 8 g of water/kg of air. After this the air must also be heated to a temperature of 15 °C, i.e. slightly upward along the left-hand vertical line in the diagram.

In the diagram of Figure 8, the situation according to Figure 6 also starts from the top of the middle vertical line in which the temperature of the air exiting the space 22 to be cooled and fed to the dryer 4 is 33 °C and the relative humidity 32%, in which case the air contains some 10.3 g of water/kg of air. In this process the air is dried before cooling, whereby we proceed towards the left, diagonally up the diagram. This leads us to the top of the left-hand vertical line, which illustrates the dried and mixed air. Its temperature is 39 °C and its relative humidity 19%, in which case it contains some 8 g of water/kg of air. After this the air must be cooled to a temperature of 15 °C, i.e. slightly upward from the bottom of the left-hand vertical line in the diagram. The diagram shows that in this so- called dry-cooling method the process according to the diagram is not at any stage near the dew point, which is depicted by a line passing along the bottom parts of the vertical lines in the diagram.

Figure 9 shows a schematic view of an equipment arrangement for a freezing space according to the invention in which all of the cooling equipment is outside the freezing space 22. Cold air circulates from the freezing space 22 through filters 8 and cold radiators 11 back into the freezing space through channels 20. Reserve air entering from the outside air is dried using dryers 4 and is conducted into the circulation air. Compressors 12 are in a separate machine room and outdoors, outside the freezing space, are effective condensers 14. In this case, the air in the freezing space is constantly dry and clean because it is continuously directed through the filters 8. Thus no impurities, moisture or ice forms in the freezing space 22. In this context, the freezing space means a space in which products can be frozen but the freezing space according to the invention is equally suited for the storage of frozen products.

Figure 10 shows a detail of the freezing space 22 in Figure 9 and its equipment. The air directed into the freezing space 22 in Figure 10 is dried in two stages such that at the first stage the air is directed into a single high-power drying apparatus 4a. After this the pre- dried air is divided up into three portions and is further dried in three second-stage dryers 4b, 4c and 4d. The first portion of the dried air is conducted from the second-stage dryer 4b through the cooling radiator 11a to the air channel 20a and onward to the loading space 47. Thus enough cold and dry air is conducted into the loading space 47 so that the doorways of the loading space 47 can be equipped with air curtains 48. As the air in the loading space 47 is cold and dry the frozen products do not melt even if they have to be kept in the loading space temporarily. Due to the dry air ice does not, at any stage, form in the loading space 47 nor does its air get foggy even though the doorways only have air curtains 48. In Figure 10 the second portion of the dried air is channelled from the dryer 4c through the cooling radiator 11 b into the air channel 20b and onward to the freezing space 22.

Similarly also the third portion of the dried air is channelled from the dryer 4d through the cooling radiator 11c into the air channel 20c and from there to the freezing space 22. Figure 10 shows that the equipment used for cooling the freezing space 22 and the loading space 47 and drying its cooling air, such as the dryers 4a, 4b, 4c and 4d, cooling radiators 11a, 1 1 b and 11c, compressors 12 and condensing radiators 14 are all located outside the freezing space 22 and the loading space 47. Thus the freezing space does not contain any of the inconvenient cooling radiators of known freezing spaces which usually have to be defrosted regularly. Because the freezing space according to the invention does not have cooling radiators, this also does away with the need to clean dust and other impurities from the cooling radiators as in known freezing spaces. According to the invention, there are air filters in connection with the inlet air cooling radiators 11a, 11 b and 11c outside the freezing space which also prevent impurities from entering the freezing space 22.

Figure 11 shows a diagram of a unit according to the invention that can be optionally used for cooling and/or drying. This kind of unit can be made mobile, for example in a vehicle or trailer 50 in which case it can be quickly and conveniently taken anywhere. The unit forms a convenient package that can also be installed, for example, in a school, office or similar. The unit has three separate air flows, which are the inlet air flow, regeneration air flow and the condenser air flow. The inlet air flow equipment includes the outside air filter 8, rotor of the dryer 4, cooling radiator 11 and inlet air fan 10. The regeneration air flow equipment includes the air filter 2, regeneration air pre-heating radiator 13, regeneration air post- heating radiator, i.e. superheat radiator 15, the rotor of the dryer 4, the exiting regeneration air's cooling radiator 16 and fan 5. The superheat radiator 15 for the regeneration air is not essential if C0₂ equipment is used in which the required regeneration temperature of some 82 °C is already achieved using the regeneration air pre-heating radiator 13. The condenser's air flow equipment includes a condenser 14 in the outside air and the condenser's fan 49.

The equipment according to the example in Figure 11 is designed such that the capacities of the compressor 12, cooling radiator 1 1 , regeneration air heating radiator 13 and condensing radiator 14 are approximately 60-70 kW. In this case the unit produces 1.9 m³/s of inlet air that has a temperature of 18 °C and humidity of 45% when the temperature of the outside air is 25 °C and has a relative humidity of 60%. The required flow of outside air for regenerating the dryer's rotor is 1.2 m³/s. The unit can be adjusted to work so that it cools and dries, or alternatively the entire capacity of the unit is used only for cooling or drying.

Figure 12 shows a cooling and/or drying unit according to the invention which is located in a trailer 50. The unit's air flows are arranged in three levels such that in the lowest level is the inlet air flow equipment, such as the outside air filter 8, the cooling radiator 11 and the inlet air fan 10. In the middle level is the regeneration air flow equipment, such as the regeneration air heating radiators 13 and 15, the cooling radiator 16 for the exiting regeneration air and the fan 5. The rotor of the drying apparatus 4 is involved in the operations of both levels.

Uppermost in the unit is a condenser 14 and its fan 49. The condenser 14 can also be positioned lower down, for example on the side of the unit.

LIST OF REFERENCE NUMBERS

1 Dryer's regeneration inlet air

2 Air filter

3 Heating radiator

4 Dryer

4a Dryer

4b Dryer

4c Dryer

4d Dryer

5 Regeneration air fan

6 Dryer's regeneration exhaust air

7 Inlet air

8 Air filter

9 Heating radiator

10 Inlet air fan

11 Inlet air cooling radiator

11a Inlet air cooling radiator

11 b Inlet air cooling radiator

11c Inlet air cooling radiator

12 Compressor

13 Regeneration air pre-heating radiator

14 Condensing radiator outdoors

15 Regeneration air post-heating radiator

16 Cooling radiator for exiting regeneration air

17 Compressor

18 Air channelled into room

19 Circulation air channel

20 Air channel

20a Air channel

20b Air channel

20c Air channel

21 Regeneration air channel

22 Space

23 Exhaust air fan

24 Exhaust air channel

25 Exhaust air 26 Adjustment damper

27 Adjustment damper

28 Heat exchanger

29 Channel

30 Fan

31 Electric radiator

32 Exhaust air fan

33 Exhaust air

34 Air channel

35 Air channel

36 Valve

37 Expansion valve

38 Valve

39 Valve

40 Heat recovery device

41 Exhaust air channel

42 Valve

43 Valve

44 Channel

45 Chilling beam

46 Fan

47 Loading space

48 Air curtain

49 Condenser fan

50 Trailer

Claims

1. A method for cooling and/or drying a space (22) equipped with an air dryer (4) and an air cooling apparatus (11), characterised in that the regeneration air of the air dryer (4) is heated using the energy attained from the inlet air (8) cooling radiator (11 ).

2. A method according to claim 1, characterised in that the heating energy required by the heating radiator (13, 15) of the regeneration air of the air dryer (4) is taken with a heat pump from the inlet air cooling radiator (11) and from the cooling radiator (16) of the hot exhaust air used for regeneration.

3. A method according to claim 1 or2, characterised in that the heat pump's compressor (12) is used to transfer at least a portion of the heat energy of the air- conditioning's inlet air cooling radiator (11) and of the energy taken by the compressor to the heating radiator (13, 15) required for the regeneration of the drying apparatus (4) rotor.

4. A method according to claim 1,2 or 3, characterised in that if the cooling power requirement of the space (22) is large, only a portion of the energy of the inlet air cooling radiator (11) is used to heat the regeneration air heating radiator (13, 15) of the drying apparatus (4) rotor and the rest of the cooling radiator's energy is channelled out through an outside condensing radiator (14).

5. A method according to any one of claims 1 to4, characterised in that if the cooling power requirement of the space (22) is low, the energy of the inlet air cooling radiator (11) is used in its entirety to heat the regeneration air heating radiator (13, 15) of the drying apparatus (4) rotor.

6. A method according to any one of claims 1 to5, characterised in that a space equipped with an air dryer (4) and an air cooling apparatus (11) can optionally be dried and/or cooled using the same equipment.

7. An apparatus for cooling and/or drying a space (22) equipped with an air dryer (4) and an air cooling apparatus (11), characterised in that the apparatus has a heat pump belonging to the cooling apparatus, which heat pump includes a compressor (12), an inlet air cooling radiator (11) and an outside condenser (14) and that the regeneration air heating radiator (13, 15) of the rotor of the drying apparatus (4) is connected to the condensing circuit of the heat pump.

8. An apparatus according to claim 7, characterised in that a regeneration air preheating radiator (13) and a regeneration air post-heating radiator (15), i.e. superheat radiator, are connected in series with the outside condenser (14) to the heat pump's condenser circuit.

9. An apparatus according to claim 7 or 8, characterised in that the apparatus includes a cooling radiator (16) for the hot exhaust air used for the regeneration of the rotor of the air dryer (4) connected in series with the inlet air cooling radiator (11).

10. An apparatus according to claim 7, 8 or 9, characterised in that the apparatus has an adjusting element (36, 39), with which it is possible to adjust the amount of energy transferred from the inlet air cooling radiator (11) to the heating radiator (13, 15) for the regeneration air of the dryer (4) rotor and/or outside condenser (14) such that the apparatus can be used optionally for the cooling and/or drying of the inlet air.

11. An apparatus according to any one of claims 1 to 10, characterised in that the apparatus contains a chilling beam (45) connected to the same circuit with the inlet air cooling radiator (11).

12. An apparatus according to any one of claims 1 to 11 , characterised in that the apparatus is a cooling and/or drying unit that can be used optionally for cooling and/or drying and the unit has three separate air flow sections,

the inlet air flow equipment are the outside air filter (8), the cooling radiator 11 ) and the inlet air fan (10).

the regeneration air flow equipment are the heating radiators (13, 15), the cooling radiator 16 for the exiting regeneration air (16) and the fan (5).

the condenser flow equipment are the condenser (14) and the fan (49), and both the inlet air flow and regeneration air flow are conducted through the rotor of the drying apparatus (4).

13. An apparatus according to any one of claims 1 to 12, characterised in that, in the cooling and/or drying unit, the inlet airflow equipment is on the lowest level, the regeneration air flow equipment on the next level and the condenser flow equipment on the top level or the side of the apparatus.

14. An apparatus according to any one of claims 1 to13, characterised in that the cooling and/or drying unit is located in a vehicle or trailer (50).