AU7234691A

AU7234691A - Dehumidifying apparatus

Info

Publication number: AU7234691A
Application number: AU72346/91A
Authority: AU
Inventors: Anthony Harry Simpson
Original assignee: Management & Guidance Services
Current assignee: Management & Guidance Services Ltd
Priority date: 1990-02-16
Filing date: 1991-02-13
Publication date: 1991-09-03
Anticipated expiration: 2011-02-13
Also published as: EP0469111A1; GB2242017A; GB9003571D0; GB2242017B; AU641475B2; WO1991012476A1

Description

DEHU IDIFYING APPARATUS

This invention relates to dehumidifying apparatus and is more particularly concerned with cooling or refrigeration dehumidifiers.

Dehumidifying apparatus is used to reduce the amount of water vapour in the atmosphere and thus is frequently employed to dry out flood damaged buildings or other enclosed areas which have become damp or soaked with water. Dehumidifying apparatus can shorten the drying time of materials including building structures ( for example bricks, concrete, timber etc. ) and any other materials having higher moisture content than is required. Such apparatus can be used to reduce the humidity level in an enclosed area in order to reduce the activity level of moisture related corrosion and to prevent deterioration, due to excess moisture absorption, for example of stored items. Dehumidifying apparatus presently available include cooling or refrigeration dehumidifiers and desiccant humidifiers. Both these types of dehumidifiers tend to have certain disadvantages. Refrigeration dehumidifiers are much less costly than the desiccant type and generally have low cost and low power consumption characteristics, but are only efficient within a specific temperature range. If the air surrounding the dehumidifier is already cold then the refrigeration dehumidifier will not work well in condensing out water from air which is already cold. Thus, refrigeration dehumidifiers operate within a limited temperature range and additionally they tend only to provide a limited air movement which tends to be in¬ sufficient on its own for the dehumidifying process to be carried out reasonably quickly. Desiccant dehumidifiers may not have some of the drawbacks which tend to be associated with refrigeration dehumidifiers (i.e. the same limited temperature range for operation does not apply) and they tend to be more efficient at low humidity levels. However, the cost of a desiccant dehumidifier may be four or five times that of a refrigeration dehumidifier of similar size and capacity and, additionally, the desiccant dehumidifier requires specialist maintenance and attention, there being much less requirement with refrigeration dehumidifiers which are generally reliable as well as being much less expensive.

It is possible to utilise dehumidifying apparatus in conjunction with other devices such as heaters and fans in order to attempt to improve the overall de-humidifying or drying-out process but the overall efficiency still tends to be lower than need be the case.

It is an object of the present invention to provide dehumidifying apparatus and a method of dehumidifying which alleviates or obviates at least one of the aforementioned, or other, disadvantages associated therewith.

According to the present invention there is provided dehumidifying apparatus in the form of a portable or transportable unit comprising a cooling or refrigeration dehumidifier in combination with a pressure developing fan or impeller.

In one embodiment of the present invention the pressure developing fan or impeller is arranged so that it does not directly interact with the working components of the refrigeration dehumidifier. Preferably, said fan or impeller is arranged in a compartment within said unit (preferably towards the bottom of the unit and underneath the dehumidifier) and, preferably, a separate air intake and separate air outlet is provided for the fan/impeller. Most preferably, and advantageously, a heater is also provided in said unit ( this heater is preferably located in the flow path from the fan/impeller ) . Additionally, the unit is, preferably provided with duct means to convey the air from the air outlet of the impeller to a location somewhat remote from the unit itself. Thus, in this embodiment the operation of the components of the refrigeration dehumidifier is unaffected by the inclusion of a fan/impeller and/or heater contained within the same unit, so that, advantageously, no new design or maximised operation parameters need to be worked out for the refrigeration dehumidifier. Indeed, it is an advantage of this embodiment of the present invention that a standard existing refrigeration dehumidifier can be utilised and incorporated into said unit with the fan/impeller and/or heater.

Although it is possible to utilise a refrigeration dehumidifier whilst other items such as heaters and fans are operated in the same enclosed area in order to enhance the de-humidifying process, as previously stated, the accompaniment of such additional devices in a room with the dehumidifier does not significantly improve drying rates and the overall efficiency is still low. This is because the utilisation of such devices separately means that each device sets up its own convection cycle and there is no real co-operation between the devices or combined co-operative effect. Additionally, there are clearly advantages in being able to carry or transport such devices together in a single unit. For example, where a heater is combined into said unit no separate exterior casing is required and the heater itself may take the form of a simple heating coil.

Preferably, and most advantageously, the refrigeration dehumidifier, the fan/impeller (and heater where provided) may all be powered from a single power source and via a standard 13 amp plug connected into a standard 240 volt 20 amp ring main.

In this embodiment, therefore, the air flow from the pressure developing fan/impeller is positioned advantageously in such a manner that it does not interfere with or upset the predetermined balance between air flow and condensing surfaces in the refrigeration dehumidifier. Instead, a balance is provided between the capacity of the dehumidifier, the heat output (where the heater is provided) and the additional air movement, tc provide seemingly optimised drying conditions.

Where duct means is provided to carry air from the fan/impeller to a location remote from the unit itself, positive air pressure points are created away from said unit thereby improving air distribution further and allowing the air returning to the negative pressure inlet points of the unit to slow to a speed which will not interfere with the working of the refrigeration dehumidifier.

Where duct means is provided as aforesaid this would usually comprise at least two sections of flexible ducting to convey air from the fan/impeller to spaced locations away from the unit itself. Preferably, the fan/impeller is a backward curved centrifugal type noted for quiet operation and pressure developing characteristics which, advantageously, does not require any specially shaped casing for efficiency. Where a heater is provided it may be of about 2 kilowatts for a domestic unit (refrigeration dehumidifier having a compressor with approximately one third h.p. capacity). Advantageously, the operation of the refrigeration dehumidifier, fan/impeller and/or heater may be controlled from a control panel (preferably located on said unit) or at least inter-related control means may be --. provided for the refrigeration dehumidifier, fan/impeller and/or the heater. In this respect a switch interlock may be provided to prevent the heater being used without the fan and/or a separate heater auto resetting over temperature switch may be provided to prevent overheating 0 in the event of failure of the fan/impeller or in the event of restriction of air passage through the unit.

Preferably, the unit comprises an internal humidistat preset to prevent overdrying and an internal 5 preset thermostat to control the temperature of the drying area. A humidistat may be provided for controlling external humidity.

Advantageously, the unit may be no wider than 750 mm 0 and no higher than 1,500 mm.

Where a heater is provided it will be preferably settable to a plurality of heat output levels since ambient temperature conditions are variable. For 5 example, the heater may be an open, wire-wound type with an electrical centre tapping given to heat options.

This embodiment of the present invention may be provided with many other advantageous features which will 0 be apparent from the following description and drawings.

In a second embodiment of the present invention said pressure developing fan or impeller is arranged to interact with the working of the refrigeration 5 dehumidifier. This design of dehumidifying apparatus will usually entail a large scale industrial unit where the design and operating parameters for the refrigeration dehumidifier are not as critical as with smaller, domestic scale equipment. For example, the apparatus may be of 5 h.p. capacity. It is believed that such a unit could be constructed at somewhere around one fifth of the price of desiccant dehumidifiers of a similar scale. In this embodiment, the unit may be provided with an air intake into the refrigeration dehumidifier as well as two side air intakes into separate fan/impeller units operating to convey air to heaters before driving the air to air outlet means. Air issuing from the air outlet means may be a combination of heated air from the impellers and dry air from the refrigeration dehumidifier. Advantageously, the power consumption of the apparatus may be balanced electronically to suit required conditions, ambient conditions and power availabity. Preferably, the unit will be arranged to operate from a three phase power supply with 9 kilowatt and 14 kilowatt options.

Many other advantageous features will be apparent from the following description and drawings.

Further according to the present invention there is provided a method of drying or dehumidifying a room or enclosed area, said method comprising operating a refrigeration dehumidifier in combination with a pressure-developing fan or impeller in such manner that the convection cycles of the dehumidifier and of the fan/impeller are mixed in order to set up a controlled drying cycle.

Preferably the air from the fan/impeller is heated and, preferably, the heated air is carried to an outlet point or points away from the refrigeration dehumidifier so that positive air pressure points are created away from the refrigeration dehumidifier in order that air returning to negative pressure inlet points to the dehumidifier will be slowed down.

Many other preferable method features will be apparent from the following description and drawings.

An embodiment of dehumidifying apparatus and a method of dehumidifying or drying-out a room or enclosed area will now be described by way of example only with reference to the accompanying FIGURES of the drawings, in which:-

FIGURE 1 is a diagrammatic representation of the operating ^• cycle of a known type of refrigeration dehumidifier;

FIGURE 2 illustrates the operating effect of the refrigeration dehumidifier of FIGURE 1 used in conjunction with a separate heater and fan; FIGURE 3 illustrates the operating cycle of de¬ humidifying apparatus in accordance with the present invention;

FIGURE 4 is a sectional schematic side view of the dehumidifying apparatus shown in FIGURE 3; FIGURE 5 is a more detailed three dimensional schematic view of the dehumidifying apparatus;

FIGURE 6 is a view similar to FIGURE 5 but shows a larger modified embodiment of the dehumidifying apparatus, and FIGURE 7 shows a three dimensional schematic view of a very substantially modified embodiment of dehumidifying apparatus which is for use on an industrial scale.

FIGURE 1 of the drawings illustrates schematically a refrigeration dehumidifier 1 which is generally of a known type. Air is circulated through the device which sets up a convection cycle as illustrated by the arrows passing into the air inlet A and through the air outlet B of the dehumidifier. The dehumidifier 1 is provided with an air-cooling arrangement ( not shown) and an evaporator (not shown) which condenses out water vapour from the air, said water vapour being fed by a condensate outlet hose H into a storage container S. As illustrated in the FIGURE the refrigeration dehumidifier operating in the room or enclosed space R provides limited air movement (as illustated by the arrows of the convection cycle) and, since the dehumidifier operates by cooling the air in order to extxact the condensate it is only operable within a limited temperature range.

FIGURE 2 illustrates what happens when the refrigeration dehumidifier 1 is used in conjunction with a heater 2 and with a fan 3 in the same enclosed space. As will be apparent from FIGURE 2 each of the separate items, the dehumidifier 1, heater 2 and fan 3 set up their own convection cycle as depicted by the arrows in the FIGURE. The inclusion of the fan 3 and heater 2 in the same enclosed space with the dehumidifier 1 slightly improves drying rates but because each convection cycle is separate the overall efficiency is still low. Heaters, when used alone, assist in the evaporation of moisture from materials but have no means of disposing of the moisture which is in the air and fans provide good air movement which can speed up the drying process, but once again have no means of disposing of moisture in the air.

FIGURE 3 shows de-humidifying apparatus 101 in accordance with the present invention, which is utilised in an enclosed area and illustrates the mixed convection cycle (illustrated by the arrows ) set up by the apparatus. The apparatus 101 is shown in more detail in FIGURES 4 and 5. The apparatus 101 has an upper section 102 which corresponds basically with a standard cooling or refrigeration dehumidifier. This works in a known manner and, therefore, will only be described briefly. The dehumidifier 102 has an air inlet 103 in which air is drawn by a fan f before being passed through outlet 105 (see the arrows through the dehumidifier section 102 in FIGURE 4) . A compressor C is provided which runs coolant through cooling coil 104 in order to cool air incoming through inlet 103. An evaporator e is provided in the flow path to the fan f and water is condensed out from the air being drawn through the air inlet 103 and passed down the condensate outlet hose H into a container S in known manner. Air from which moisture has been extracted is fed out of the dehumidifier through outlet 105.

The unit 101 as shown in FIGURES 2 to 5 is a one third h.p. unit and, in this size of unit there is an important balance to be maintained between the dehumidifier air throughput and the cooler surface area of the cooling coil 104 and temperature. Therefore, in order not to upset this balance (but to improve the efficiency of the dehumidifying process) the unit is provided with a centrifugal, pressure developing fan or impeller F, which is housed in a separate compartment 106 at the bottom of the unit 101. As should be clear from FIGURES 4 and 5 a dividing baffle or wall 107 is provided to separate the refrigeration dehumidifier 102 from the compartment 106 housing the fan F. A separate air inlet 108 is provided for the fan F which draws air into the compartment 106 and delivers the air to a heater 109 ( 2 kw in this case) before the air is fed to flexible air distribution ducts 110. The fan F itself is chosen to be as quiet as possible and is a rotating fan which is of a backward curved centrifugal type noted for quiet operation and pressure developing characteristics. Additionally, this design of fan does not require any specially shaped casing for efficiency. The heater 109 is an open, wire-wound type with an electrical centre tapping giving two heat options. Heat output selection is desirable because of variable ambient temperature conditions. Air from the heater 109 is delivered to two outlets 111 (see FIGURE 5) on the front of the apparatus 101 and the flexible ducts 110 (2 ducts shown) can be connected to the outlets 111. Thus the air inlet 108 is on a fan inlet negative pressure side and the air outlets 111 are on a positive pressure side. The connection of the flexible ducts 110 has the effect of moving the air outlet of the fan F and therefore the positive air pressure points away from the unit 101 and thus improves air distribution. Spacing the air outlet points from the fan away from the unit 101 allows the air returning to the negative pressure inlet points of the unit (more particularly to inlet 103 ) to slow to a speed that will not interfere with the operation of the dehumidifier 102. FIGURE 3 shows a general flow path for the mixed convection cycle in which one of the air outlet points of one of the ducts 109 is trained under the floor boards of the room R in order to help dry out damp in the walls of the room. Warm air under pressure is forced out of the ends of the ducts 110 and mixes with damp air being drawn through the fan inlet 108 and also mixes with damp air being fed through the inlet 103 to the dehumidifier. Dry air from the dehumidifier outlet 104 is circulated and mixed with the damp air and warm air (from ducts 110) into the dehumidifier inlet 103.

Although the embodiment of dehumidifying apparatus

101 as described and illustrated includes a heater and flexible ducting the operation of the dehumidifier 102 would be improved even if the heater and/or ducting were not provided. However the provision of the heater and ducting as shown allows an extended area of drying creating positive and negative pressure points, controlling and mixing the air flows to seemingly the best advantage as shown in FIGURE 3. Thus the apparatus 5 101 encourages a good mix of dry air, damp air and warm air without affecting the operation of the dehumidifier 102. In this embodiment an internal humidistat (not shown) preset to prevent overdrying is positioned in the compartment 106 near the inlet 108 in the incoming 0 airflow. Additionally, an internally preset thermostat (not shown) to control the temperature of the drying area is also positioned in the unit near the inlet 108 in the path of the incoming air.

5 The dehumidifying apparatus 101 has a central control panel 112 to control the operation of the dehumidifier 102, fan F and heater 109 in interdependent manner. In this embodiment a switch interlock is provided to prevent the heater 109 from being used 0 without the fan Fand a separate heater auto resetting over temperature switch is provided to prevent overheating in the event of fan failure or restriction of the air passage. Additionally, provision may be provided for external humidity control by humidistat. 5

The unit 101 is no wider than 750 mm and no higher than 1500 mm so that it may easily be transported from place to place and pass through standard size doorways. Advantageously, the unit operates from a single power C source and has a maximum power consumption not exceeding 13 amps, 240 volt A.C. The thermostat is set to stop the air from rising above a temperature of 30°C. The unit 101 is portable and transportable manually and by commercially acceptable transportation standards. The 5 unit can be controlled to prevent overdrying through low humidity levels and overheating of the drying area. The apparatus 101 can be set up to give approximately five air circulations per hour in a 100 of space.

To summarise, the apparatus 101 provides: (a) a proven dehumidifier arrangement 102 to collect moisture from the air, (b) a heater 109 to provide the operational temperature band for the dehumidifier 102 and to encourage moisture evaporation from materials, (c) a pressure developing fan to distribute the heated and dried air and to create air pressure variations, assisting temperature induced convection currents and thus setting up a controlled drying cycle, (d) a heater output capable of raising the temperature of the volume (as dictated by dehumidifying capacity) from 0°C to within the temperature band required by the dehumidifier to operate efficiently.

An operation example for the apparatus 101 is as follows:

For a dehumidifying capacity capable of drying an area 100 cubic metres the working temperature will be between 15°C to 30°C (optimum) and the heater requirement should be capable of raising 100 cubic metres from 0°C to 5°C to 30°C (in a sensibly sealed area).

The addition of the flexible air distribution ducting 110 allows the effective drying area to be increased and makes the best use of the generation of positive and negative air pressures, these pressures being used to improve the drying cycle since conditions will be set at such that convection currents will move in order to equalise that pressure distribution.

FIGURE 6 shows a modified embodiment of the dehumidifying apparatus 201. This apparatus is generally similar to apparatus 101 but is a 1 h.p. model.

The operation of the unit 201 is similar to the operation of unit 101 but in this example two vertically arranged pressure developing fans F' (only one shown) are provided instead of the single horizontal fan F in apparatus 102. Additionally, two heaters 109' are provided rather than a single heater and the apparatus is provided with wheels W as shown. The heaters 109' are provided on each side of the unit 201. One of the heaters 109' is powered from the dehumidifier power supply circuit and the other is powered from a separate circuit.

In the dehumidifing apparatus 101,201, the dehumidifier heater and fan have been selected and assembled so as not to upset, in the dehumidifier section, the balance between the condensing surface area and the air speed/volume produced by a separate fan unit. However, for a larger scale unit this balance is not so important and FIGURE 7 represents a much larger scaled unit in which there is an interaction between the air inflow to the humidifier and the air inflow to the fan and heater unit to thereby produce a mixture of air from the refrigeration unit from the heaters at the outlet side of the unit. FIGURE 7 shows a schematic arrangement for dehumidifying apparatus 301. The general scheme and placement of the various components of the apparatus should be generally evident from FIGURE 7. In this example there are two fan units 302 which take in air through associated side vents in he apparatus 301 and air flowing through the dehumidifying section 303 is drawn through the fan units 302 with air from outside into two compartments 304 to be heated by heater units 305 before being passed out of the apparatus via outlets 306, to which flexible ducting (not shown) can be attached. This large scale unit 301 will operate from a three phase supply and may have a 9/14 kilowatt option, but preferably will have variable power options from 5 to 14 kilowatts, and the power consumption will be balanced electronically to suit required conditions, ambient conditions and power availablility.

It is to be understood that the scope of the present invention is not to be unduly limited by the particular choice of terminology and that a specific term may be replaced by any equivalent or generic term where sensible. Further it is to be understood that individual features, method or functions or combinations of same related to the dehumidifying apparatus or parts thereof might be individually patentably inventive. In particular, any disclosure in this specification of a range for a variable or parameter shall be taken to include a disclosure of any selectable or derivable sub¬ range within that range and shall be taken to include a disclosure of any value for the variable or parameter lying within or at an end of the range. The dehumidifying apparatus may be utilised as an air conditioning unit.

Claims

1. Dehumidifying apparatus characterised in that it is in the form of a portable or transportable unit comprising a cooling or refrigeration dehumidifier in combination with a pressure developing fan or impeller.

2. Apparatus as claimed in Claim 1 in which the pressure developing fan or impeller is arranged so that it does not directly interact with the working components of the refrigeration dehumidifier, and, preferably, in which said fan or impeller is arranged in a compartment within said unit, and, preferably, in which the fan or impeller is towards the bottom of the unit and underneath the dehumidifier, and, preferably, in which a separate air intake and separate air outlet is provided for the fan/impeller, and, preferably, in which a heater is provided in said unit, said heater, preferably being located in the flow path from the fan/impeller.

3. Apparatus as claimed in Claim 2 in which the unit is provided with duct means to convey the air from the air outlet of the impeller to a location somewhat remote from the unit itself, and, preferably, in which the air flow from the pressure developing fan/impeller is positioned in such a manner that it does not interfere with or upset a predetermined balance between air flow and condensing surfaces in the refrigeration dehumidifier, and, preferably, in which positive air pressure points are created away from said unit thereby improving air distribution further and allowing the air returning to the negative pressure inlet points of the unit to slow to a speed which will not interfere with the working of the refrigeration dehumidifier, and, preferably, in which said duct means comprises at least two sections of flexible ducting to convey air from the fan/impeller to spaced locations away from the unit itself, and preferably, in which the fan/impeller is a backward curved centrifugal type.

5 4. Apparatus as claimed in Claim 2 or 3 in which said heater is of about 2h kilowatts for a domestic unit (refrigeration dehumidifier having a compressor with approximately one third h.p. capacity).

0 5. Apparatus as claimed in any one of the preceding claims in which the operation of the refrigeration dehumidifier, fan/impeller and/or heater where provided is controlled from a control panel (preferably located on said unit) or at least inter-related control means is ^**. provided for the refrigeration dehumidifier, fan/impeller and/or the heater, and, preferably in which a switch interlock is provided to prevent the heater (where provided) being used without the fan and/or a separate heater auto resetting over temperature switch is provided 0 to prevent overheating in the event of failure of the fan/impeller or in the event of restriction of air passage through the unit.

6. Apparatus as claimed in any one of the preceding 5 claims in which the unit comprises an internal humidistat preset to prevent overdrying and an internal preset thermostat to control the temperature of the drying area, and, preferably, in which a humidistat is provided for controlling external humidity, and preferably in which 0 the unit is no wider than 750 mm and no higher than 1,500 mm, and preferably in which said heater is settable to a plurality of heat output levels, and, possibly in which the heater is an open, wire-wound type with an electrical centre tapping giving two heat options, and, possibly, in 5 which the refrigeration dehumidifier, the fan/impeller

(and heater where provided) are all powered from a single power source and via a standard 13 amp plug connected into a standard 240 volt 20 amp ring main.

7. Apparatus as claimed in Claim 1 in which said pressure developing fan or impeller is arranged to interact with the working of the refrigeration dehumidifier.

8. Apparatus as claimed in Claim 7 which is a large scale industrial unit, and preferably in which the apparatus is of 5 h.p. capacity, and preferably in which an air intake is provided into the refrigeration dehumidifier as well as two side air intakes into separate fan/impeller units operating to convey air to heaters before driving the air to air outlet means, and preferably in which the power consumption of the apparatus is balanced electronically to suit required conditions, ambient conditions and power availability, and preferably in which the unit is arranged to operate from a three phase power supply with 9 kilowatt and 14 kilowatt options.

9. A method of drying or dehumidifying a room or enclosed area, said method characterised by operating a refrigeration dehumidifier in combination with a pressure-developing fan or impeller in such manner that the convection cycles of the dehumidifier and of the fan/impeller are mixed in order to set up a controlled drying cycle, and, preferably in which the air from the fan/impeller is heated.

10. A method as claimed in Claim 9 in which the heated air is carried to an outlet point or points away from the refrigeration dehumidifier.