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1. WO1992016799 - PERSONAL ENVIRONMENT SYSTEM

Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters

[ EN ]

PERSONAL ENVIRONMENT SYSTEM

This invention relates to environmental systems, and more particularly to an air distribution unit for use in such systems.

There is increasing concern over the comfort of personnel in the work environment, both in terms of air quality on the one hand and temperature and humidity levels on the other. With the trend toward open plan designs and sealed buildings, it becomes more difficult to ensure the comfort of individual workers. Most large buildings have centralized air conditioning units that control humidity and temperature levels and also filter out undesirable contaminants. Due to the volume of air to be .processed, it takes a considerable time to condition the air in the entire building, and
furthermore workers often have different individual comfort levels. Not all occupants of a building have the same comfort requirements, and however good the building design differences in temperature levels can arise between different parts of a room.

Smoking is often a problem. In many instances this is banned altogether due to its undesirable impact on non-smokers. However, such a ban can detrimentally effect the efficiency of habitual smokers.

An object of the invention is to alleviate the aforementioned disadvantages by allowing the individual to exercise some degree of control over his or her personal environment.

According to the present invention there is provided a personal environment system for creating a user-definable local environment within a localized zone in an ambient space, comprising a modular housing ountable in said localized zone and having an air inlet, an air outlet incorporating a diffuser for distributing conditioned air into said localized zone, an air flow channel between said air inlet and said air outlet, and a channel for a thermal fluid for supplying or carrying away heat; blower means for causing air to flow through said air channel; a heat exchanger between said air flow channel and said thermal fluid channel and including a thermoelectric heat pump to effect transfer of heat between air flowing through said air flow channel and said thermal fluid channel; and user- controlled means for setting the amount of heating or cooling applied by said heat pump to air flowing through said air channel to permit the user to control the air temperature within the localized zone according to personal comfort requirements independently of the general air temperature of the ambient space.

The housing may be in the form of a desk
mountable unit that can draw air either from the room or from an air source located in a under-floor plenum, for example. This arrangement gives the user nearly complete control over the local temperature in his or her zone, which may be warmer or colder than the ambient temperature in the room. This is particular useful for large open plan offices where many workers often have different needs.

The heat pump is preferably in the form of a semiconductor Peltier-effect device thermoelectric device electrically controlled by the individual.

The thermal fluid can either be air, which is discharged away from the localized zone, or liquid from a thermal reservoir, which can be mounted below the desk of the user in the case of a workstation. The thermal reservoir can be in the form of a tank for water, preferably incorporating a substance such as glycerin to improve the heat capacity of the thermal fluid.

A filter is preferably mounted in the unit to remove particulate and other contaminants in the air flowing through the air channel.

In another embodiment, the personal environment system is in the form of a wall-mounted unit, for example located in front of a workstation in an open-plan office space. This unit contains the air intake, blower and heat pump, and can draw air from the room through and direct it through discharge nozzles into the localized zone.

The unit preferably comprises an occupant sensor and a memory for storing the preferred settings of the user. The system is de-activated when the user leaves the workstation and automatically re-activated on his or her return at the same settings.

The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings, in which:-

Figure 1 is an overall perspective view of one embodiment of a desk-mountable personal environment system in accordance with the invention;

Figure 2 is a perspective close-up view of a desk mountable unit;

Figure 3 is a cross section through a coupling assembly showing a floor-mounted air distribution unit as a source of air for the personal environment desk unit;

Figure 4 is a cut away view the desk mountable showing the heat exchanger;

Figures 5 and 6 are views of a second embodiment of a desk mountable unit incorporating a retractable lamp;

Figure 7 shows a different form of grill plate for the desk mountable unit;

Figure 8 is a circuit diagram of the fan control circuit;

Figure 9 shows the variation in perceived colour as red and green LED's are selectively energized;

Figure 10 is a diagram of a circuit for energizing the LED's.

Figure 11 is a perspective view of a wall-mounted unit;

Figure 12 shows the arrangement of heat exchanger plates in the unit shown in Figure 11;

Figure 13 shoes part of the blower and air
conditioning unit for the wall-mounted unit shown in Figure 11;

Figure 14 is a more detailed view shoeing the front panel layout of the wall-mounted unit;

Figure 15 is an exploded view showing parts of the interior of the wall-mounted unit;

Figure 16 is a block diagram showing the control circuit for the blower in the wall-mounted unit;

Figure 17 is a general block diagram of the system layout; and

Figure 18 is a more detailed diagram showing the main control functions of the wall-mounted unit.

Referring now to Figure 1, the desk mountable personal environment unit 20 is connected by a flexible hose 21 to a fresh air supply 14. The fresh air can be drawn from an under floor plenum space 3 (Figure 3) communicating with a central air conditioning system, ductwork, or the ambient air in the room. Figure 3 shows the air being drawn from the plenum space 3 through a fan unit 11 coupled to a flexible hose 21 through outlet 14.

The air is directed through the desk mountable unit 20 and out toward the individual through the angled, triangular grill 22, which serves as a
diffuser, into a localized zone defined by an
individual workstation. The desk-mountable unit 20 contains a heat pump connected by hose lines 23 to a water tank 29 mounted beneath the desk. A pump (not shown) circulates water acting as a thermal fluid through a channel in the desk-mountable unit 20 and the water tank 29.

To provide improved efficiency the heat transfer medium may consist of a mixture of about 15% by weight glycerin and water. The glycerin water mixture has a substantially higher heat capacity than water alone and therefore more efficiently transfers heat.

A high efficiency filter (not shown) is also mounted in the base of the housing for removing
particulate and other contaminants from air flowing through.

The desk mountable unit 20 is shown in more detail in Figure 2. The unit comprises an upright triangular housing 25 mounted on a rectangular base 26 provided with control knobs 27. The upper part of the housing 25 is beveled to provide the triangular, angled plate 22 with circular air distribution holes 24 through which air flows into the localized zone.

Within the housing 25 is located a heat pump-heat exchanger arrangement 28, described in more detail with reference to Figure 4.

Referring now to Figure 4, the heat pump
arrangement 28 comprises a central closed triangular core 34 with a fluid inlet and outlet 30, 31 at the bottom and top respectively. The inlet and outlet are connected by lines to water reservoir 29. The core 34, which defines a thermal fluid channel, is angularly offset relative to the housing 25 so that the apices of the core 34 are directed towards the midlines of the faces of the triangular housing 25.

A series of thermoelectric elements 32 are glued on each of the faces of the core 34. The
thermoelectric elements are commercially available semi-conductor Peltier effect devices, for example, such as the Marlow Ml 1069 unit. The current through the elements 32 is adjusted by means of the controls 27 (figure 2) on the front of the unit.

Trapezoidal-shaped heat exchangers 33 of machined aluminum block have sets of vertical parallel fins mounted on the outer faces of the thermoelectric
elements 32 to provide, with core 34, the complete heat pump assembly 28. The fins define between them
portions of an air channel for air flowing through the housing.

In operation, the user controls the level and direction of current through the thermoelectric
elements 32, causing heat to be withdrawn from or returned to the liquid flowing through the core 29. As a result, the incoming air flowing up through the housing 25 in the portions of the air channel between the fins of the heat exchangers 33 is heated or cooled. The unit thus gives the individual personalized control of his local temperature, which can be either lower or higher than the ambient temperature in the room. This is particularly useful in large open-plan offices, where many work stations are located in one room.
Since a heat pump is employed, any energy extracted from the air is stored in the water reservoir 24 for subsequent return to the air. As a result, the unit operates at high efficiency.

Rather than take admit air from the under-floor plenum space 3, the desk-mountable unit 20 can draw air directly from the room. Since the object of the unit is not to provide self-sufficient heating or cooling as the primary air conditioning source, but rather to provide a modest temperature differential as a
secondary source, in the order of ± 10°C relative to the ambient air, the thermal fluid can also be air that is drawn in from the room and discharged away from the user.

Figures 4a and 4b show a modified version of the desk mountable unit incorporating a retractable lamp. In this version, one half of the top of the unit 25 is beveled to provide grill 22. A triangular lamp 34 is mounted on an articulated arm 35. The lamp 34 has a shape complementary to the remaining portion 35 of the top of the housing 25 such that in the closed position (Figure 5) it may be mated with the top of the housing to close the grill 22.

The base 26 of the unit is provided with different coloured LED's 35, for example, red, amber, and green or blue to indicate the status of the unit. Red normally indicates the heating mode, blue or green the cooling mode, and amber the neutral mode in which heat is neither supplied to nor withdrawn from the air stream flowing through the unit. Alternatively, by placing red and green LED's side by side so that they form a common source of light, and energizing them selectively with the circuit shown in Figure 10, a gradation of colours from green to red can be generated as shown in Figure 9. In this arrangement, green represents maximum cooling, red maximum heating, and the various shades of amber in between correspond to the intermediate heating, cooling states, or neutral states of the unit. The same effect can be achieved with a single LED capable of changing colour depending on how it is energized.

The desk-mountable unit 25 permits the individual to exercise additional personal control by supplying air into the localized zone at a temperature which may be higher or lower than ambient temperature or the temperature of the air coming from the central air-conditioning system through the plenum space. It can direct the air flow toward the individual at a
controllable rate of zero to 80 cfm according to
personal preference. For this purpose a separate fan 36 can be incorporated in the base of the unit or can be mounted externally.

The thermoelectric heat pump provides a
coefficient of performance (COP) of 2.5 to 3.5 and provides up to 5°C cooling or 7.5°c heating. This is not sufficient to act as a primary source, but it is sufficient to permit an occupant to vary his or her local environment in accordance with personal comfort requirements. In a hot, stuffy room, a 5°C temperature differential is quite noticeable.

Returning to the Figure 3 embodiment, part of the housing 20' is arranged as a separate unit containing thermoelectric cell and fan unit 36, which is mounted directly under the desk. In this embodiment the main housing 20 mounted above the desk acts as a passive air distribution unit.

As shown in Figure 7, the top plate 22 can be provided with machined channels 38 forming an outlet grille instead of the circular holes shown in Figure 1. The walls channels 38 can be set at a different angles to eject the outflowing air in different directions as shown by the arrows. This arrangement provides
adequate comfort without directing the air directly toward the individual, which might create the
impression of a draft.

The efficiency of a heat pump depends on the temperature differential between that source and sink. Since the personal environmental units are only
required to operate over a relatively small range on the ambient air, their efficiency can be very high.
For instance, if the ambient is at 21° C, it is unlikely that any particular individual will want to work in an environment different from the ambient by more than a few degrees.

The desk mountable units can be used to maximize comfort levels in an open-plan environment, such as may be found in a large building while at the same time maximizing efficiency. A common complaint of
individuals is the stuffiness present in modern tightly sealed, energy efficient buildings. By providing a localized source of freshly filtered and conditioned air, the personal environment unit reduces this
problem. Each individual has personal control over his or her immediate environment.

The unit is environmentally friendly since it uses a thermoelectric heat pump, it does not employ CFC's. It operates independently of the central air supply system at a power load of less than 170 watts.

If desired, the device can be activated by an infra-red occupancy sensor designed to activate the desk-mountable unit according to preset conditions when an individual is present at the desk. The user can set up an environment according to his or her needs. This information is stored in memory. When the user leaves the desk, the unit is de-activated, and when he or she returns, the personal environment unit is automatically re-activated at the preset levels.

Figure 11 shows a personal environment unit in the form of a wall-mounted unit 60, for example adapted to be fitted into a wall forming part of a workstation partition.

The wall unit 60 comprises a central blower 62, which draws in air from the room immediately in front of the occupier of a localized zone defined by the workstation and passes it through heat exchanger units 63 to directable outlet vents 64. The blower 62 has an a.c. powered, phase-controlled motor to provide a wide range of speed variation at minimum noise levels. It operates at zero to 150 cfm (cubic feet per minute) .

The airflow can be controlled manually through control units 65, which control the speed of the fan or electronically in response to sensor inputs. For example, the unit can be provided with an infrared sensor to sense the presence of an individual at the workstation, in which case the unit can be activated at a preset level.

Air drawn in by the blower is passed through heat exchanger units comprising an aluminum block in the form of a median conductive plate 71 with
thermoelectric semiconductor heat pump elements 71 glued to the face thereof. A stack of heat-exchanger fins 72a, 72b is arranged on each side of, and
perpendicular to, the control plate 70. Air flow paths 73a, 73b forming portions of the air flow channel through the unit are defined between the fins of each stack 72a, 72b. On one side of the heat exchanger, 73a, the air flows to the nozzles 64, which direct the air into the direct vicinity of the person at the workstation. On the other side, 73b, the air flows to a discharge outlet (not shown) away from the
workstation. Since the unit is only intended to provided a localized temperature differential above or below the ambient temperature it does not matter that excess heat or cold is discharged into the room away from the user. Some users may prefer temperatures higher than the ambient, whereas some users may prefer lower temperatures. These two classes of user will cancel out. If there are more users on one side of the median temperature than the other, the room temperature will rise or fall as the case may be, in which case the primary system will be activated to restore the ambient conditions.

The thermoelectric semiconductor heat pump
elements 71 are controlled by the control units 65 on the front of the wall unit 60. By varying the
magnitude and direction of the current in the
thermoelectric elements 71, heat can be either from or added to the heat flowing out of outlets 64, and with a complementary heating or cooling of the air flowing through the path 73b to the discharge outlet.

Figure 14 shows the general layout of an improved embodiment of the wall-mounted unit. The blower 62 is centrally located as in Figure 11, with thermoelectric heat pumps 64 diametrically disposed on either side of the blower 62. Control and power units 65 are located adjacent the heat pumps 64. Directable diffuser nozzles are located on either side of the unit.

A control panel 79 is located below the blower 62 on the front of the unit. The control panel includes a Smartlite® LED 67, which glows red if the air is being heated, blue if it is being cooled, and amber if no heat transfer is taking place. The remaining buttons allow the user to set the level of heating or cooling according to personal needs and other environmental factors in the workstation. For example, the control panel 69 can also set the lighting level and the degree of background noise provided by a white noise
generator, not shown.

The control units 65 include a memory for storing the user's preferences. Infrared occupancy sensor senses the presence of an occupant. When the occupant leaves the workstation, the unit is de-activated, and when he or she returns the unit is re-activated at the previously set levels.

Figure 15 is an exploded view that helps show the internal configuration of the unit 60.

Figure 16 shows the control circuit for the blower 62. This is phase-controlled by triacs 90, 91 and can run at extremely low noise levels.

Figure 17 shows an overall block diagram of the system. The control panel 69 has buttons 69a that allow the level of the various environmental systems to be preset. The buttons operate digital systems that ramp up or down according to the dwell time of the user's finger on the buttons.

The system is controlled by central control unit 100, which incorporates a microprocessor and keyboard entry logic unit 101. Figure 18 is a more detailed circuit diagram of the system.

The wall unit thus provides localized heating or cooling for individual and in particular workstations and is well suited to large open plan offices, where different workers may have different needs.

Each worker can operate in a personal environment that is at a slightly different temperature from, either above or below, the ambient temperature. If the ambient temperature is set at the median comfort level of the occupants of a room, the some workstations will take heat from the ambient and some will return heat depending on the preference of the individual. On balance the room temperature will remain constant. If there is a greater amount of cooling or heating as a result of more workstations being in the cool or heat mode respectively, the conventional room thermostats will ensure that more or less general heating or cooling is applied to the room ambient as appropriate.