JPS6111580A - Zero-point cooler - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [No use of the invention! II? ) The present invention relates to a dew point cooler for cooling Mlr□ of air, which is a) arranged so that the air to be cooled passes along the outside of the tube while exchanging heat; b) Means for passing precooled tertiary air into the inside of the reading tube; C) Means for introducing water into the reading tube from above to form a water film on the inner wall of the tube. means; d) means for discharging moistened secondary air; and @) a heat exchanger comprising means for passing at least a portion of the cooled primary air into the space to be cooled.

[Background of the invention]

A similar dew point cooler is itself disclosed in U.S. Pat.
It is known from No. 9. This involves cooling the primary air from the atmosphere and directing it into the relevant space, while at the same time directing the secondary air stream (already approximately at the desired temperature) to the heat exchanger and the water It has been proposed to carry out air conditioning (cooling) of the space by allowing the primary air flow to be cooled through the evaporation of the air.

Similar principles but slightly different structures are disclosed in U.S. Pat.
74060 bow, West unique pestle application publication number 2432308,
and Dutch Patent Application No. 7711149.

These depend on the structure of the heat exchanger used (tube rows or plates as heat exchange surfaces) and the evaporation of water in the secondary stream.
, differ from each other in terms of the mist of small water droplets, the wall surface for retaining the water, the alternating supply of water to both halves of the heat exchanger plate, or the continuous spraying of water.

In each of these methods, the secondary stream is moistened by evaporating water and cooled to a lower temperature than the primary stream. The resulting temperature difference allows the secondary stream to pick up heat from the primary stream, and the latter is thus cooled. As a result of this heat absorption, the secondary stream becomes unsaturated with water vapor again, allowing new water to evaporate and absorbing additional heat from the primary stream, and so on.

As a result of the cooling of the primary stream, the temperature of the primary stream decreases while the absolute humidity of the air stream (in units of 9 degrees Fahrenheit per air) remains constant.

Since any appreciable heat transfer between the primary and secondary air streams as a result of thermal conduction resistance requires a temperature difference between both streams, and this temperature difference is The achievable primary air outlet temperature is often due to the diversion of the primary flow and by moistening the secondary air flow whose inlet temperature is equal to the outlet temperature of the primary air flow. higher than the dew point of air.

- Only in the ideal case can the outlet temperature of the secondary air be equal to its dew point. This is the origin of the name dew point cooler.

This air cooling method is cheaper than more common mechanical refrigerators. This is because the latter uses more energy.

Some of these publications additionally state that the cooled air may be partially or completely subjected to a subsequent cooling treatment by a mechanical refrigerator to condense a portion of the water vapor. It states that it should be done. This combined cooling can be advantageously used when the absolute temperature of the atmospheric air is higher than that of the desired cooling air. Considerable savings can also be achieved in that case. In fact, mechanical refrigerators only need to be used when necessary to lower absolute humidity.

In all other cases only the much cheaper dew point cooler is used.

Despite these obvious and significant advantages, this glaze dew point cooler has, to the applicant's knowledge, never been used in practice on either a small or large scale.

The reason for this it has never been shown. Nevertheless, dew point coolers are only suitable for use if the heat exchanger is of high efficiency (and given the relatively small temperature difference between the air streams that must necessarily occur). It is clear that this can only be achieved using large heat exchange areas.

It can be seen that in all cases reported in the literature, the proposed heat exchanger has an effective surface area on the primary flow side that is essentially not different in size from the effective surface area on the secondary flow side.

Under these circumstances, the heat exchanger will be too large in most cases.

Moreover, in practice it proves extremely difficult, if not entirely impossible, to create a secondary stream saturated with water vapor. Such a flow will of course have a minimum secondary temperature.

[Purpose of the invention]

The object of the invention is to provide a dew point cooler that provides optimum cooling using a compact structure.

For this purpose, the dew point cooler defined at the outset is adapted according to the invention to periodically supply water with the means of distribution C), the tubes having an element on the side in contact with the primary air. It is assumed that the ratio of the side surface area to the inside surface area of the pipe in which the pipe is provided is greater than 3:1.

Surprisingly, a combination of measures according to the invention is described.

FIG. 1 is a vertical cross-sectional view of a dew point cooler. There, several vertical pipe sections are marked with the number 3.

- The next stream 1 enters these sections from the left and then flows horizontally through them. The secondary (wet) flow enters the device from the top right corner, then flows down the tubes in the rightmost section as indicated by arrow 2, then through the tubes in the other sections before passing through the tubes in the upper left section. Exit this device at the corner.

The water to be evaporated is lifted from the vessels 4 (FIG. 1) below each section by means of pumps 5 to a device 16 and from there to the uppermost tube sheet 5 with a rising edge. On these tube sheets, the water is distributed over each tube by a water distributor 13, so that the inner wall surface of each tube in that section is covered with a layer of water, along which a secondary air flow is accompanied by evaporation of the water ( (in an upward or downward direction), the required heat of evaporation is extracted from the primary flow which is in contact with the outer wall of the tube and the fin plates. The portion of water that has not evaporated is returned to the container 4.

The origin of the primary flow depends on how the dew point cooler is included within the air conditioning system.

In a simple embodiment, the primary flow may consist of air drawn in from outside air, which is cooled in a heat exchanger and then passed from the right-hand side of FIG. 1 into the space to be cooled.

To maintain the desired temperature in the space, a portion of the air present in the space, say 10% per hour, is continuously evacuated and used as a secondary stream 2.

During the passage of some sections 3 water evaporates there [7° At the same time this secondary flow absorbs heat from the primary flow, so that when the next offshore, the secondary flow is cooled It will be heated. It is precisely this temperature increase that allows more and more water to evaporate in the secondary flow, and the highly humidified air flow to exit from the left end at a temperature higher than the temperature of the space to be cooled. I have something to do.

This highly humidified air is also unsuitable for use in this cooling method.

However, it is extremely important that the water vapor content of the cooled primary stream does not change during passage through the heat exchanger.

Good heat exchange requires that heat is first transferred from the primary (dry) stream to the (usually metal) wall. The amount of heat transferred is then directly proportional to the product α1F1. F here
l is the heat transfer surface area, and α1 is the heat transfer coefficient. When this heat passes through the bulkhead material, the same 1: of heat must be transferred from the wall to the secondary (wet) stream, and the amount of heat transferred is then directly proportional to α2F2. Again, F2 is the heat transfer surface area and α2 is the heat transfer coefficient.

W, ] Lcjdcnfro, st no evaporative cooling analysis and improvement with 111m evaporative cooling analysis number Warme-un
d Stoffixbertragung12 (197
9) From page 5-23, when there is an evaporating water film on the wall surface, the heat transfer coefficient when heat is transferred from the wall to the air stream is the same as the heat transfer coefficient caused by convective heat transfer to the same wall. It is known to be a multiple. L@ld@nfroflt describes a minimum ratio of 3 for saturated air and greater than 5 for unsaturated air.

Apart from the difference in convective heat transfer between the flow inside the tube and the flow around the circumference of the (finned) tube, it is based on the above that in the dew point cooler according to the invention the outside dry surface area and the inside It may be necessary to use a heat exchanger with a wetted surface area ratio greater than 3:1.

A condition for this is that the heat exchange surface on the side of the secondary air flow should always be covered with a thin layer of water, since the ratio O α2/c11 depends on the conditions of the primary air introduced: The aim is F1/F'2 to α2
This will approximate A1. The value of the ratio of the outer surface area of the tube to the inner surface area is preferably between 5:1 and 10:1.

As the value of the outer surface area, the effective outer surface area can be used, which can be calculated using published formulas for the design of tubes in which the elements are installed.

All of the above publications on dew point coolers agree in describing a F1/F'2 ratio of less than or equal to I:1. This is probably the reason why none of these proposals have found practical application.

If we design a heat exchanger with F, /F2 of about 6, then for the same capacity, F, = 1/3 of the volume of the heat exchanger with F2]
It is found that only /4 volume is required.

To create the required heat exchange surface area differences, it is possible, as in known design methods, to start with tubes with fins attached and then to combine these finned tubes into larger units, for example fin batteries. It is. Known exchangers of this type are usually designed for significant differential pressures between the two exchange gas streams. However, in a dew point cooler, this differential pressure is at most a few millimeters per million, which allows for an extremely lightweight structure.

The usual method of making fin batteries is as follows: Holes are punched in a metal plate, such as an aluminum plate, with a thickness of 0.2 to 1.0 mm, such as 0.25 mm, and these often also have a collar. be. The fin plate is then transferred onto the 6 tube and the tube is expanded either mechanically or hydraulically to tighten the fins to the tube. These finned tubes are then attached to a conventional tubesheet.

This structure can also be used in the case of the present invention.

Preferably, however, the heat exchanger is assembled from a plurality of plates with rows of apertures, each aperture having a collar that fits into the apertures in the adjacent plate, and the plates stacked together to form a set of collars. taken together to form a plurality of tubes interconnected by the remaining portions of the plate serving as fins.

The aperture in the form of a collar can effectively be between 2o and 40m1 in diameter and the length of the collar can be between 4 and 7trrm.

For structural reasons, the shape of the aperture is often circular. The diameter of 30 tubes and the collar length of 6 tubes are extremely effective.

When the collars are suitably shaped, each collar can be inserted approximately half its length into the underlying tube as shown in Figures 4a and 4b. Six tubes would then be unnecessary and the tube and fin combination could be made into a more compact and substantial design at much lower cost. Hereinafter, the term "tube" shall be understood to include "tubes" in which such collars are partially inserted into each other.When the collars can be inserted into each other with only a slight push, it is easy and solid. Structures can be created in which the various tube sections are in well-sealed, face-to-face contact.

Pipes, however they are designed, must be able to provide a thin layer of water on their inner surface, which should preferably cover the entire pipe wall and be as uniform in thickness as possible. It should be. Furthermore, all tubes should naturally be moistened to the same extent. The water supply system must therefore not be sensitive to centering errors or disturbances in the water surface on the top tubesheet.

The above US patent proposes the use of a plate exchanger with a cloth covering on the wet side. It also states that better results can be obtained by supplying water periodically rather than continuously. The structure described in this patent has the disadvantage that the plate surface is covered with a wet cloth and can be kept evenly moist, but it still has a greater resistance to heat flow than a water film directly on the metal. be.

In a preferred embodiment of the dew point cooler according to the invention, means are provided for using a portion of the cooled primary air as secondary air.

It is also possible to use means for humidifying the secondary stream (air) before supplying it to the secondary side of the tube. Suitable means provide for direct evaporation of water in the stream. Nine examples are wet mats or water curtains.

In particular, the humidifying means is present at six inversion points, ie, at the secondary stream after the cooled air has been split into primary and secondary streams.

Water distribution is achieved by a water distributor consisting of two short concentric tube sections (30, 32) at the top of each vertical tube, the inner one 3
0 extending into or around the tube and tightened in a seal thereto, the outer one resting on the uppermost tube sheet, and one on its lower edge extending into the annular gap between both tube sections. The inner one 30 is provided with a plurality of spaced apertures 34 along its circumference connecting the annular gap 31 with the interior of the tube, It has been found that this can be effectively carried out by slightly spaced above, which is another feature of the invention (6th meter
, 6b, 6c). These apertures 34 distribute the supplied water along the circumference of the tube. Gas flowing through the tube can then enter and exit through the inner tube section. A funnel-shaped portion 35 is preferably provided at the top of the inner tube. These water distributors according to the invention have the advantage of extremely low pressure losses.

As shown in FIG. 1, one or more containers 4 for the water to be evaporated are provided below the tube row 12, as in known dew point coolers, in which the unevaporated water collects. The water is supplied from there to the top tube plate 7 on which the water distributor 13 rests.

The tubesheet is provided with a rising edge.

Although a specific embodiment of four pipe sections is shown in FIG. 1, other numbers of sections may be used and the primary flow 1 and the secondary flow 2 may vary in this manner. It becomes clear that it is possible to pass through such classifications while satisfying the requirements. When the tube bank consists of a plurality of sections 3, 3 which are traversed one after the other by the secondary stream 2, it is advantageous that each section has its own vessel 4, since each section corresponds to a different temperature for the secondary stream. Useful. - The next stream 1 is then passed between the extratubular plates.

Various devices can be used to ensure that water is supplied to the top tubesheet periodically, ie, in the right amount at the right time and at the right intervals.

The simplest method is a pump that is switched on and off in a known manner. However, this type of switching system is prone to failure. U.S. Patent No. 2107280
No. 1 describes a device with a double tilting tank. This system works satisfactorily, but because it has moving parts, it is subject to wear and tear and will not function reliably for very long periods of time.

According to the present invention, the preferred system is a self-launching siphon system.

The principle of this type of system is shown in FIG.

The receiver R is filled with a continuous water supply, for example by a pump supplying water from a container 4 below the pipe in question. As soon as the water in the receiver reaches level 1, the siphon H initially begins to operate simply as an overflow channel. However, the siphon is equipped with a recoil levee that directs the water flowing on the bottom of the siphon toward the ceiling of the siphon, thereby trapping the air volume above the recoil levee. Because the velocity of the water is relatively high, the pressure in the jet is lower at the recoil bank, thus drawing air from the top of the siphon.

As a result, the siphon quickly filled with water and
The state shown in the figure is reached. From that moment on, the siphon is rapidly and completely filled, after which the discharge of water through the siphon quickly reaches its maximum.

This discharge continues until the receiver R is emptied to water level 2, air can again enter from the left end of the siphon, and the supply of water to the pipe is stopped.

In this way, an amount of water determined by the size of the receiver R can be supplied at regular intervals.

Experiments have shown that in some cases the siphon activation time is so long that the correct ratio between siphon activation time and cycle period cannot be achieved.

In fact, as mentioned above, a recoil levee exists within the siphon. This causes air to be removed and allows the siphon to start quickly and easily, but at the same time the levee can block the exit after the siphon is started and interfere with the flow of the effluent water.

For this reason, in another preferred embodiment of the invention, a
*See Figures 8b and 9) The higher siphon has a higher peak than the smaller siphon B, and the smaller siphon B is self-activated, but the larger one is not.

The larger Siphon has no recoil dam. The smaller siphon is activated as described above, but now the larger siphon, which is mounted next to or above, in addition to itself, also has one or more connecting passages, such as the connecting passage V shown in FIG. 8c. After that, empty it directly so that the larger siphon will also start up quickly. Due to the absence of obstructing recoil banks and the large outlet diameter, the discharge capacity of Siphon A is such that short discharge periods are achieved.

To summarize, the substance of the combination of the major (main) siphon A and the minor (secondary) siphon B is that the minor siphon essentially activates itself first and then the major siphon. The evacuation of water through the minor siphon is of secondary magnitude. Large siphons, on the other hand, are designed to enable the evacuation of large amounts of water in a limited amount of time.

Draining water in a short time is important. This is because it is necessary to periodically inject a large amount of water into all (wet) tubes of the heat exchanger so that the entire inner wall is exposed to form the desired water film at the same time. .

During the humidification period, normal flow of air in the tubes with heat exchange with the secondary flow is possible for a short time; only after that is normal heat exchange continued. . The periodic supply of water not only keeps the water belly in check, but also removes all dirt and deposits from the pipe walls.

In order to ensure that the water can be distributed as evenly as possible to all the tubes, the water is not poured directly into the tubes, but for example onto the top tube plate 7 (see Figure 1), which is provided with a raised edge. . From the tubesheet, water flows between various water distributors 130;
Elevate the air gap between the inner and outer pipe sections of the water distributor. The flow resistance within the air gap allows each tube to admit only a limited amount of water, which is distributed along the circumference of each tube through the apertures 34 (see FIG. 6). When each tube has taken in the desired amount of water, the water level in the tube sheet will have fallen below the edge of the opening 34 and no more water will be admitted into the tube until the next water supply. There is.

In practice, the size of the small siphon will be chosen so that it will be activated by the applied water supply and the large siphon will be chosen so that the receiver can be emptied in less than 10 seconds, preferably about 5 seconds.

Because of the high velocity of water exiting the large siphon, at some point in practice (depending on the location of the siphon outlet above the tubesheet) a surge of water occurs from which the water finds its way into the tubesheet. The result of a surge is that the tube rows located in the immediate vicinity receive an excess amount of water and the more distant tube rows receive an insufficient amount of water. Narrow outlet 1 for water from the siphon
It has been found effective to receive the tube 1 in a tank 10 (FIG. 10) which is open into the water along the edge of the tube sheet 12.

When the main siphon (FIG. 9a) starts operating, it fills the tank 10 (FIG. 10) up to the overflow edge 13 at the first moment. When this edge is reached, the water begins to flow over it and is distributed over the entire length of the tubesheet. Although the outlet 11 is very narrow, the instantaneous water supply from the main siphon is so large that the water rises to a higher level in the tank, and this is accompanied by an increasing thrust on the overflowing water. . This forces the air above the overflow to escape downwards, allowing the overflow to operate like a full-fledged siphon. The result is an even distribution of overflow water over the length of the tubesheet, as well as an enhanced intermittent effect of the main siphon.

The ultimate result of the above combination of a water receiver with primary and secondary siphons on the one hand and a water collection tank with a gap-like outlet on the other hand is that all the associated pipes are completely wetted in 3 to 4 seconds. It is.

The dimensions of the secondary siphon determine the minimum water flow rate required to operate the siphon. The volume of the receiver is then determined in relation to the desired cycle period.

Also for water collection tanks, activation of the siphon occurs above a given (instantaneous) flow rate. In practice, with the size of the water collection tank used in dew point coolers, this rate of water flow is such that it is impossible to use the water collection tank as a stable water flow determination device with the appropriate cycle period, runoff time, and correct flow rate. It is as large as possible.

For large equipment where water usage is proportionately large,
In the above combination of receiver and water collection tank with paired main and sub-siphons, the paired main and sub-siphons extend to the highest required water level in the receiver, allowing water to overflow from below the rim of the cover. An alternative is a (vertical) overflow tube (see FIG. 11) which is covered (for example with a spigot) so that it can enter the flow tube. The overflow pipe shall form a water seal within the collection tank. The receiver is filled with a continuous stream of water. From the moment the water flows away from the receiver through the overflow pipe, the water tank is filled with the same flow of water and the water level rises both at the water tank and at the outlet of the overflow pipe.

As soon as the water collection tank begins its siphon operation, the water level in the water collection tank falls and at the same time the water level in the overflow pipe outlet also falls.

As a result of this lowering of the water level, the air present in the overflow pipe and cover moves downward.

Since the pressure of the air in this volume is constant, the water flows into the tank.
As a result, the overflow tube begins to operate as a siphon.The remainder of the air in the overflow tube is also evacuated at that time and the receiver receives full siphon capacity, allowing air to enter the tube from the lower edge of the overflow tube. It will be vacant until

Using the above combination, the best result is that the dimensions of the collection tank are such that the water flow discharged by the collection tank siphon is equal to or slightly greater than the water flow supplied by the siphon-operated overflow pipe, and both siphons are This is obtained when their operations are completed almost simultaneously.

In large air conditioning systems, the space load is met by recirculating air within the space, which air is cooled in one or more central air treatment units, and the required fresh outside air is conditioned in a separate treatment unit. The air is then passed to the main recirculation system or mixed directly with recirculation air.

When installing this or these fresh air treatment devices with a cooler according to the invention in combination with mechanical finishing cooling (so-called dew point cooler), the recirculating air treatment device is designed without mechanical cooling and the main space load is It is entirely possible to provide this with the dew point cooler according to the invention.

Therefore, the present invention also provides a space air conditioning unit, which adjusts the temperature and moisture of air from the outside to desired values,
a first section for passing the air so treated into the space, and a second section for circulating the air in the space to readjust the temperature to the desired value, returning the majority of the recycled air and discharging a small portion. in the first section, the air from the outside is cooled in a dew point cooler according to the invention and, if necessary, the temperature and/or moisture content of the air is lowered to the desired range by mechanical cooling or The second category also relates to those characterized in that the cooling operation is carried out using the dew point cooler according to the invention as described above. A system of this type is shown in FIG.

The present invention also provides an air conditioning unit for a space, which has a section that adjusts the temperature and moisture of a mixture of air and outside air existing in the space to desired values, and returns most of the mixture and exhausts a small part. It also relates to a unit characterized in that, in some cases, part of the cooling process in said section is carried out using a dew point cooler of the type defined above, after which, if necessary, the temperature and moisture content of the air is further lowered in a known manner. An insight into the energy savings obtained using both of these embodiments is shown in the following example, where the two types of air conditioning units mentioned are compared to a device using only mechanical ventilation.

[Embodiments of the invention]

Example Heat generation (space load) is 100 kW, air circulation amount is 30
Starting from an office space to be air conditioned of 15 inches of recirculated air with 000 m3/'h and a minimum amount of fresh air.

Literature (by Recknagal, Handbook of Heating and Air Pl Control Technology, Oldenburg Verlmg,
Based on the pleasure curve diagram from Munich, 1974), the desired spatial conditions for the office are 25°C/45°C. Outside air (
- fresh air) conditions are estimated to be 30°C and 150%.

Water vapor shall not be generated within the office space (
Absolute moisture content 1ix = constant). Air recirculation amount is 3000
0 m3/h - 36000 kg/h, therefore the mass flow is 1
0 to 97 seconds.

Heat production is 100 kW (-space load). Enthalpy increase -10 kJ/kg: Corresponds to a temperature rise of 10°C. The space air inlet temperature must be 15°C.

Method 1: Mechanical cooling only (control) Fresh air and recirculated air are mixed before passing through the cooling unit. The mixture therefore consists of 85 inches of space air at a condition of 25°C/45 inches and 15 inches of fresh outside air at a condition of 30°C and 150q6. The enthalpy of the mixture is hM = 51 k
J/kg. The inlet conditions are 15° C./85% and the enthalpy is 9 in h −38 kJ/. The enthalpy drop due to cooling is 13 kJ/9. The mass flow of the mixture is mm=10 kg/sec.

Therefore, the desired cooling capacity q1=mm(ΔH)−13ok
It is W.

Based on experiments with a test arrangement of dew point coolers, it has been determined that it is possible to cool the air stream to 1.5° C. below the associated wet bulb temperature.

This data shows that in this embodiment, this space load can be completely covered by dew point cooling.

The enthalpy drop is 10kJAI. Also, the difference between the inlet temperature of the primary air and the outlet temperature of the saturated secondary air is 1.5°C by adjusting the mass flow ratio between the primary air and the secondary air accordingly.
It is also known that it can be maintained at The secondary air enthalpy rise is then 7O-38 = 32 kJ/kg and the mass flow ratio must be 3.2 to sink, ie the secondary air flow in the main dew point cooler is -Lx3eoo.

3.2 =10800kg/h.

This amount must be supplied to the system as fresh air. This fresh (external) air at the original condition 30° C. 150% is also mechanically cooled to the condition 21tl::/85% by dew point cooling and subsequently to the condition 15° C./85%.

The enthalpy drop during this mechanical cooling process h(-b,
-56-38 = 18 kJ/kg and the mass flow of fresh air in the cylinder is mv = 10800 kg/h - 3 kg Aae. Cooling capacity is q2=mv(Δh)=3X
18 = 54 kW. Expressed as a percentage of the cooling capacity required by Method 1, this is □a o X 1
00 chi becomes 41.5 chi.

Statistical data for the Dutch national situation show that the same absolute water content as in the above example occurs for 27 hours per year. For 22 hours of that time, conditions of 21°C/85°C can be achieved using a dew point cooler. This shows that the calculated cooling capacity of 54 kW is required for only 22 hours per year, and that, apart from the extra 14 hours, the remainder can always be filled by using less energy.

It therefore makes sense to introduce the term "cooling degree time" here. It is defined as the product of the number of hours a certain volume of air must be cooled to reach a given condition and the temperature range (in degrees Celsius) over which such cooling occurs. It is a measure of the amount of energy required for such cooling.

According to the above statistical data, in this embodiment, the cooling of the office space by method 2 is 3720 times per year.
It can be calculated that cooling degree time is required.

Recknagal, in his publication cited above, states 8175 cooling degree hours per year for Cooling Method No. 1.

In method 1, the number of cooling degree hours is 36000 kmh
15% = 5,400 kg/h, while the remaining 30,600 kg/h must be cooled by 10°C during the cooling period of about 3.5 months (8 a.m. to 6 p.m.). . This total number of cooling degree hours (approximately 1000) corresponds well to that found in FIG. 10 for a 15° C. higher air temperature. The latter number is 10,150 and the number of cooling degree hours is 10,150.

In method 2, the calculated number of cooling degree hours is 1080
Applies only to 0 kgA.

Therefore, in both methods, the annual cooling energy q
The interrelationship between 1 and Q is as follows: and means the energy savings in the cooling method proposed by the present invention.

Note: The above examples do not take into account that the outside air condition is often not extreme, such as 30°C and 150°C, and the requirement for space cooling is small. The table presented by Reeknagel takes these effects into account.

In summary, in the second cooling method proposed here, 1. the total cooling capacity to be installed can be reduced to about 40% of that in the case of mechanical cooling, 2. the number of full load hours of this reduced cooling system is It is of course also possible to first pass the mixture of space air and fresh air through a dew point cooler and then cool it mechanically, resulting in energy savings of as little as 40 hours per year in the worst case scenario3. It is. The dew point cooling principle involves that the mixture must be drawn from about 70 inches of space air and about 30 inches of fresh outside air. The ental ♂- of this mixture is h = 53 kJA. Cooling to a temperature 91.5°C higher than the associated wet bulb temperature is 1
Means cooling to 7°C (enthalpy h = 44 kJ/kg). So the enthalpy drop is 9k
J/ is 9.

Based on the final temperature to be reached of 25 DEG C. (i.e. 1.5 DEG C. below the temperature of the mixture), the enthalpy rise of the secondary air stream is 76-44 = 32 k, y/kp.

- the mass flow ratio between the primary and secondary air flows is mm/'m 1
=32/9 must be mt = 0.28 mm
(Therefore, the mixing ratio of 70%-30% is correct). mm and m! The difference is the amount of recirculated air, which is equal to 36,000 kg, which is m.
m-n3. =(1-0,28)mm=36000, so mm=500000kF! A also m,
-14,000 kg/h (see Figure 12).

As a result of the dew point cooling process, the mixture of space air and fresh air reaches a condition of 17°C/85°C. Inlet condition 15℃/8
In order to produce 5 chi, this amount of air (36,000 kg) is required.
/h or 10 kg/see) followed by mechanical cooling. The enthalpy drop there is 44-38=6
kJ/klI. Mechanical cooling capacity is q3-10.6
-60kW. Expressed as a percentage of the cooling capacity of the first method, this is: τX100%=46%.

Similar to method 2, in this example 1852 cooling degree hours are calculated, which is equivalent to 36000 hours of air.
This applies to kliJ/h. The relationship between the required mechanical cooling energy Q on an annual basis and the first method is as follows: The energy savings are therefore also considerable (more than 80%) in this method. The energy savings are slightly less impressive in method 3 compared to method 2. While this is true, method number 3 on the other hand provides significant savings in capital investment. This is because there is no separate fresh air dew point cooler.

Finally, when using dew point coolers it should be taken into account that the energy required for transport is slightly higher, which, in addition to the primary useful air, is used as a secondary stream after cooling. This is because the amount of air must be taken in, and secondly, the pressure drop in the heat exchanger is greater than that of conventional cooling devices.

The construction of the cooling device according to the invention is extremely suitable for use as a heat recovery device in winter. The fresh air supplied flows around the tube, while the used space air is passed into the tube.

Thus, if necessary, the condensed water can flow down along the inner circumference of the tube and be collected in a collector provided.

Moreover, as a heating device, the tubes can be washed regularly to remove any deposited deer dust.

When operating for heat recovery, the ratio between rain and air flows is as a rule equal to 1. Due to the surface area increase by the fins on the dry side of the heat exchanger, the heat transfer coefficient calculated for the surface area of the tube is mainly determined by the heat transfer coefficient on the wet side (inner side) and is numerically approximately equal to it. This, along with the large proportion of tubes in the heat exchanger, increases the total heat transfer and allows the efficiency of the heat exchanger to be as high as 80-90 degrees.

[Brief explanation of drawings]

FIG. 1 is a vertical section through one embodiment of a dew point cooler according to the invention. FIG. 2 is a diagram illustrating the use of a dew point cooler as part of an air conditioning installation. FIG. 3 is a diagram illustrating the use of a dew point cooler as part of an air conditioning installation. FIG. 4a is a diagram showing the use of a dew point cooler as part of the present invention; FIG. 4b is a top view of the tubesheet shown in FIGS. FIG. 5 is an exploded view of a heat exchanger used in a preferred embodiment according to the invention; and FIG. 6a is a partial cross-section of a water distributor used in a preferred embodiment of the present invention; FIG. 6b is a cross-sectional view of the water distributor taken along line 1 [b-1b of FIG. 6a; FIG. Figures 78 and 7b are top views of the water distributor shown in Figures 78 and 7b, showing the water supply means that can be used according to the invention. Figures 8a, 8b and 8c show further water supply means that can be used according to the invention, in combination with a water distribution device. O shown (Figures 1 and 5) 1...-Secondary air flow, 2...Secondary air flow, 3
... Vertical pipe section, 4... Container, 5... Pump, 6
... Bottom tube plate, 7 ... Top tube sheet, 12 ... Tube row, 13 ... Water distributor, 16 ... (middle) device (Fig. 6) 30 ... Concentric Pipe inner side, 31... annular gap, 32...
・Concentric tube outside, 33...opening (32), 34...
Opening (30), 35...Funnel shaped part (Figures 7 to 9a, 9b) R...Receptacle, H...Siphon, 1...Upper water level, 2...Lower water level , D... Recoil dike, A... Large siphon, B... Small siphon, ■... Connection passage (Figures 10-11) 10... Tank, 11... Outlet, 12...・・Tube plate, 13
...overflow edge

Claims (1)

[Claims] 1. A dew point cooler for cooling a flow of air, comprising: a) a vertical dew point cooler arranged so that the air to be cooled passes along the outside of a tube while exchanging heat; a row of tubes; b) means for passing precooled secondary air into the interior of the tubes; c) means for introducing water into the tubes from above to form a water film on the inner wall surface of the tubes; d) moistening. and e) means for passing at least a portion of the cooled primary air into the space to be cooled; is adapted to periodically supply water, the tube is provided with an element on the outside in contact with the primary air, and the ratio of the outer surface area of the tube with the element to the inner surface area of the tube is 3: A dew point cooler characterized in that the dew point is greater than 1. 2. The ratio of the outer surface and inner surface area of the tube is 5:1 to 10.
A dew point cooler according to claim 1 in the range of: 3. The heat exchanger includes a horizontal plate arranged with a plurality of apertures,
Each aperture has a collar that fits into the aperture in the adjacent plate, and the plates overlap to form a set in which the collars combine to form a plurality of tubes that are connected to the fins. 3. Dew point cooler according to claim 1, characterized in that it is connected by a remaining part of the plate serving as a dew point cooler. 4. The water film forming means includes a water supply, the supply comprising a water receiver that is filled substantially continuously during operation and a self-starting siphon for periodically discharging the contents of the receiver. A dew point cooler according to any one of claims 1 to 3, characterized in that: 5. The receiver is provided with two siphons, the first siphon being self-starting and, when activated, sucks air from the second larger siphon, thereby activating the second siphon. The dew point cooler according to claim 4, characterized in that: 6. A long container is provided below the siphon outlet.
Claims characterized in that the container is provided with a siphon on one side, the inlet and outlet of which extend laterally along one surface of the uppermost tubesheet in the direction of the flow of secondary air on the tubesheet. The dew point cooler according to item 4. 7. There are two concentric tube members, the inner one extending into or around another tube and capable of being sealed and attached to it, and the outer one being supported by a tube sheet; and the lower edge thereof is provided with one or more apertures reaching the annular gap between the two tubes, and the inner tube has one or more apertures connecting the gap and the inside of the tube or are arranged at intervals around the circumference thereof. A water distributor used in a dew point cooler characterized by having multiple holes. 8. A dew point cooler for cooling a stream of air, comprising: a) an array of vertical tubes arranged to pass the air to be cooled along the outside of the tubes with heat exchange; b) means for passing precooled secondary air into the interior of the tube; c) means for introducing water into the tube from above to form a water film on the inner wall surface of the tube; d) moistened secondary air e) means for passing at least a portion of the cooled primary air into the space to be cooled; and e) means for passing at least a portion of the cooled primary air into the space to be cooled; extending into and sealingly attached to the inside or circumference of the tube, the outer one being supported by a tube sheet, and having one or more openings in its lower edge extending into the annular gap between the tubes. means according to c), comprising a water distributor provided with holes, the inner tube having one or a plurality of holes arranged at intervals around its circumference connecting the gap and the interior of the tube; is adapted to periodically supply water, the tube is provided with an element on the outside in contact with the primary air, and the ratio of the outer surface area of the tube with the element to the inner surface area of the tube is 3: A dew point cooler characterized in that the dew point is greater than 1.