Split Air Conditioner
The American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) has formulated the official definition of air conditioning as "the process of treating air to control simultaneously its temperature, humidity, cleanliness and distribution to meet the requirements of the occupants, process or product in the conditioned space." Typically an air-conditioner is used to cool air, but it can also be used to provide heat.
In the following, a detailed description will be given. It will be appreciated that the figures are for illustration only and are not in any way restricting the scope of the disclosure. Also it is possible to combine features from different described
embodiments to meet specific implementation needs.
Air-conditioners come in many different forms. A split air conditioner has separate indoor and outdoor units connected with pipes for the refrigerant. In a Split-system air conditioners there is an indoor unit comprising a (evaporator) heat exchanger. The indoor unit is separated by some distance from the outside-environment
(condensing) heat exchanger. Fig. 1 illustrates the two split units when cooling a room. The indoor unit is normally a rectangular, undifferentiated box used with a remote control. The air conditioning market is growing rapidly. The airflow in the indoor unit of a split air-conditioner affects both the efficiency of the air conditioner, and also how the user perceives the efficiency. The efficiency goes up when air travels quicker through the heat exchanger and release heat to it. But in the same time the noise of the unit goes up. The airflow should be adjusted so that there is a good and fast enough air exchange in the room, yet not be so high that it is perceived as a negative, artificial air rush. The unit noise should also be kept as low as possible. In addition, there is a minimum limit when the airflow is so low that the credibility of the unit is questioned based on lack of feedback.
The air is thrown longer and with stronger flow when it is directed. How the air is spreading in the room depends on if the unit is heating or cooling.
The thermodynamic principle behind today's air conditioners is vapor-compression cycles of a medium called refrigerant. It is a closed refrigeration cycle where heat is extracted from the refrigerant in a low temperature part and released from the refrigerant in a high temperature sink. The refrigerant enters the compressor where the temperature rises. It then continues to a condenser, the high temperature heat sink, that a fan blows air through. The air is released out into its surroundings, taking the heat with it. The enthalpy is decreased when the refrigerant turns from vapor to liquid. The refrigerant enters an expansion valve, where the temperature drops significantly before it enters the evaporator. A second fan blows air through the evaporator and out into the surroundings. The refrigerant keeps expanding, and keeps its temperature by absorbing the heat from the air, that then blows out cooled. In Fig. 2, components of a split-air-conditioner for cooling air are depicted. Thus, the indoor unit comprises an evaporator heat exchanger. The outdoor unit comprises a condenser heat exchanger. Between the heat exchangers of the indoor and outdoor units a compressor and an expansion valve (capillary tube) are inter-connected. Both the indoor unit and the outdoor unit can further be provided with fans to increase the air flow in the respective units. Other components such as air filters can also be provided. Inverter technology can be used to automatically adapt the compressor capacity to the current need for cooling or heating. Compressors in units without the technology either run on maximum capacity or are shut off. By adding the inverter technology the unit becomes more efficient and the noise has a higher quality.
In general there are some identified problems with existing split air-conditioners. For example users find the energy consumption from a split air conditioner expensive. It is difficult for the user to comprehend what unit capacity is enough for their space. The air quality and rush of air is perceived as artificial. The air conditioner takes up a lot of visual space in the user's home but its design is not appreciated.
In accordance with some embodiments an indoor unit with a generally round frontal shape is provided. The indoor unit is essentially round in the plane of the wall or ceiling on which it is to be mounted. In other words when mounted a user will see a round shape when looking at the indoor unit from in front of it. A round design can
help supporting an improved air-flow in the room. The air can for example be directed in all directions out from the indoor unit. In particular air can be directed in 360 degrees out from the sides of the circular indoor unit. Also inlet air can be received in 360 degrees at the sides of the indoor unit. Because the air inlets and air outlets can be made relatively large and air can be blown along the walls or the ceiling of a room, the indoor unit can be made very silent. The indoor unit will also be well suited to not blow air directly out into a room. This is advantageous in particular in a bedroom, where it is desired to have a silent and comfortable environment without any air- streams that can be felt by a sleeping person. In Figs. 3a - 3d some different embodiments with a round indoor unit for a split air- conditioner are depicted.
In Fig. 3a, a round indoor unit with a heat exchanger surrounding a center fan. The center fan can be across flow fan, but it can also be an axial fan or a radial fan. In Fig. 3a the center fan is configured to drag in air through a surrounding, essentially circular heat exchanger.
In Fig. 3b small fans drags are provided to drag air through heat exchangers. The heat exchangers can be essentially rectangular and the fans can for example be cross flow fans.
In Figs. 3c and 3d, air enters the indoor unit from the sides and exits the indoor unit through the center. The heat exchanger is placed to cover the outlet. In Fig. 3c a fan drags air from all sides and the fan is located after the heat exchanger in the air stream. In Fig. 3d the fan is located before the heat exchanger in the air stream.
Regardless of the solution, the essentially circular cover of the indoor unit can be designed to let both the inlet air and the outlet air enter the indoor unit from the side of the cover. This is illustrated in Fig. 4. The overall size will depend on how large the heat exchanger has to be to reach the desired efficiency. In accordance with some embodiments the air inlet is 360° around the perimeter of the cover of the indoor unit. In accordance with some embodiments the air outlet is about 180° around the perimeter of the circular indoor unit. In some embodiments the air outlet is about 360° around the perimeter of the circular indoor unit. . In some embodiments the air outlet is in the range from 180° to 360° around the perimeter of the circular indoor unit.
The heat exchanger capacity increases with the area that connects it to the air. In accordance with some embodiments the heat exchanger is made essentially round. In accordance with some embodiments the round heat exchanger is split in parts. For example it can be split into two identical half circles. In some embodiments the coils of the heat exchanger in the indoor unit are bent at the circular perimeter of the essentially round heat exchanger. This is depicted in Fig. 5. By constructing the essentially round heat exchanger of the indoor unit with the coils bent in accordance with Fig. 5, it can be ensured that no oil is caught in the coils.
In some embodiments the heat exchanger sides are angled by compressing the inner part. The heat exchanger can then be tilted. The fins can then be pushed together since they cross the tubes. In some embodiments notches are provided that enable the compression of the inner part of the heat exchanger. In one exemplary
embodiment each cut provides an approximate 2 mm compression per coil pair.
Further, by selecting a radial fan additional advantages can be achieved. The radial fan push air 90° from the center out towards all sides. Which air direction is best for the unit correlates with how the outlet functions. As has been realized by the inventor it is for some applications advantageous to create a good room air distribution by looping the air along the sides and to avoid air directed straight at the user. By using a radial fan as depicted in Fig. 6, the air direction can be supported, because the radial fan is designed to direct the outlet air out to the sides.
In accordance with some embodiments the cover is designed to direct the output cold air cold air upwards and out into the room for a maximum natural airflow in the room. The air outlet can further be designed to direct warm outlet air downwards for a maximum natural airflow in the room. In accordance with one embodiment the air outlet is formed around the perimeter of the essentially round indoor unit. The outlet is provided with a ring encompassing the perimeter of the cover. The ring is movable and adapted to open/close an
upper/lower sector of the outlet. For example, if the heat exchanger of the indoor unit is cooling a 180° opening upwards is open. If on the other hand the heat exchanger is warming the inlet air, a 180° opening downwards is open. One way of
implementing such an opening mechanism is to provide a movable ring. The ring can be is divided in two sectors of 180° each. A motor can be adapted to rotate the ring.
In another embodiment, the opening mechanism is formed by two half rings. By rotating one of the half rings the air outlet is opened. The opening can be performed by a motor. Again, which of the half-rings that are opened can be set to depend on if the heat exchanger is warming or cooling the air. A mechanism with two rings is depicted in Fig- 7.
In the embodiment of Fig. 7 the air outlet is split in two symmetric parts across the horizontal line. The ring now consists of two half rings. One motor is positioned so it opens one side at a time by applying force with an extender. The motor can be a DC step motor. The use of a step motor can make it possible to open/close the outlet openings without the need to use sensors. Further, springs, in particular spiral springs, can be added to the axis to provide smooth movements. When one side is opened the other side stays shut. Different opening mechanisms can be used. For example the spring power can be set larger than the power the airflow applies on the movable half ring. This means the half ring will stay shut if the motor does not force it open. The other option is to add a bottom part to the extender. While the extender rotates and pushes down on the opening half ring, the extender applies a support from underneath on the closed half circle. This is depicted in Fig. 8. In Fig. 8, the extender, here blue, can be shaped to open one side while keeping the other one closed. Here with the motor and fastener to the right, positioned on the middle of the right side of the unit's side. The upper half ring is here tilted. The tilt can for example be about 10°. In another embodiment the opening mechanism is made more stable without spring movements.
In accordance with one embodiment, air is directed through a heat exchanger and in through the center of a radial fan. The heat exchanger can be essentially round and may be split into two or more sub-assemblies as set out above. The fan spreads out the air 360° and an inner wall directs the air out from the unit, as showed in Fig. 9. In Fig. 9 the left picture illustrates the unit when it is cooling and the right picture illustrates a heating unit.
In accordance with some embodiments the outlet opening is constrained so that the air inlet is larger than the outlet. In particular the air inlet can be about twice the size of the air outlet. The part that counts as the inlet is the smallest path of which the air
flows into the unit. This is between the fan and the wall. This can be viewed in Fig. 10.
In Fig. 10 an exploded view of an indoor unit for a split air-conditioner is depicted. The unit in Fig. 10 is adapted to be mounted on a wall. The unit can also be designed to be mounted in a ceiling. The unit in Fig 10 comprises a wall support, a housing having an essentially circular shape, a heat exchanger having an essentially circular shape, an opening mechanism for the outlet air, an axial fan and a front cover. The indoor unit can also comprise air filters. The filters can be the same as in today's units. Further electronics can be provided. The electronics can be placed in upper center. The electronics can be connected to a display placed in center behind the front cover. Further a water collection system can be provided. The water collection system can be a part of the housing.
In accordance with some embodiments the airflow is never directed towards the user, but focused for optimal air distribution in the room, in particular a bedroom. It uses the surfaces around to travel greater distance for less work by the fan. It also makes use of the temperature that the surfaces of walls and ceiling radiate.
The air goes in 360° from the sides on the back of the round unit, see Fig. 1 1 . In this way the filters are not directly visible from a straight view. In Fig. 1 1 , the air outlet is closed. The air can be pushed out 180° upwards and out towards the ceiling when the unit is cooling the room, see Fig. 12. In Fig. 12 the ring is opened upwards. Since hot air rises there will be a natural distribution of the air. The surface of the ceiling helps the air to travel further with less velocity. When the unit is heating it pushes out the air downwards and out for the same reasons.
As set out above, the outlet mechanism consists of an outer ring that is split in two across the horizontal centerline. The outlet is covered by fabric that is attached to the half rings as well as to a center surface that is fixed to the unit housing.
One DC step motor rotates an extender that has two functions. The extender applies force on one of the half rings to open it, while the other half ring is kept closed by the extenders other side. The half rings rotate around two axes, one on each end, following the same horizontal line. Spiral springs are attached to each axis for a smooth movement.