Split type Room Air Conditioner

SPLIT TYPE ROOM AIR CONDITIONER

See Fig. 3. The present trend in the Indian market is to go for the Split Type of the air conditioning system. It is built in two parts: Cooling Unit and Condensing Unit and hence the name Split System. Split Type Room Air Conditioner is also known as Split Package Unit.

A split package unit is designed with the fan and cooling or heating coil in one equipment section and the condenser as well as the compressor in another section.

 

See Fig. 4. The cooling unit section is located in the room. The condenser and  compressor are placed in a remote location either indoors or outdoors.

 

1. COOLING UNIT (INDOOR UNIT)

1. Evaporator Coil and Capillary Tube

The High Pressure Low Temperature (HPLT) liquid refrigerant from the condenser is passed to the capillary tube. . In the capillary tube the refrigerant expands. The Low Pressure Low Temperature (LPLT) liquid refrigerant then passes to the evaporator.

2. Evaporator Fan

Evaporator fan draws air continuously from the inside of the room through an Air Filter. The air is forced to pass over the evaporator coil by the fan and is cooled by the refrigerant. Consequently, the refrigerant evaporates by absorbing the heat from the air.

3. Mounting of Cooling Unit

Cooling unit may be floor mounted, wall mounted or ceiling mounted, depending on the requirement.

4. Controls

When a controlled atmosphere is required in air conditioning, the humidity of the air is varied. When dry air is required, it is dehumidified by cooling or by dehydration. In the latter process, the air is passed through absorptive chemicals such as silica jel. Air is humidified by circulation through water sprays.

2. CONDENSING UNIT (OUTDOOR UNIT)

1. Compressor

High temperature evaporated refrigerant from the evaporator is drawn by the suction of the compressor. The compressor compresses it and delivers it to the condenser.

2. Condenser Coil

The condenser can be air cooled in the case of room air conditioner or water cooled in the case of centralized air conditioner. If a water cooled condenser is to be used, the condenser is provided with connections for either city water or well water. For an air cooled condenser, these connections are not required.

3. Condenser Fan

The condenser fan draws the atmospheric air from the exposed side. The High Pressure High Temperature (HPHT) refrigerant passing inside the condenser condenses by giving-off the heat to the atmospheric air.

To avoid any flashing of liquid refrigerant, a receiver in the liquid line is recommended, where the distance between the condensing unit and cooling unit exceeds eight meters.

 

3. INSTALLATION

 There can be a number of combinations for the installation of cooling and condensing units, depending on the location and site. However, the following three combinations are very common in practice:

• Cooling unit and condensing unit at same level

• Cooling unit being at higher elevation than condensing unit and vice versa.

Combination-1: This is similar to a unitary air conditioning system with extended suction and liquid line.

Combination-2: Normally, the maximum recommended height of the cooling unit when compared to the condensing unit is 8 meters.

Moreover, it is advisable to provide a suction line riser at the outlet of the evaporator to prevent liquid refrigerant from draining to the compressor during off-cycles. This would be an additional protection apart from the suction line.

Combination-3: Here, in addition to the proper selection of liquid line and suction line, an oil trap on the suction line, near the evaporator outlet should be provided, if the elevation between cooling unit and condensing unit exceeds 3 meters However, the recommended elevation is 8 meters maximum.

 

4. ADVANTAGES

1. Installation: No constraints on the installation of the split type air conditioner, as the condensing unit can be located in any remote place.

 2. Noise-Free Operation: Noise free operation, because of remote location of the condensing unit.

 3. Wall Opening: No breakage or opening in the wall necessary.

 4. Flexibility of Use: Feasibility of using multiple evaporators with single condensing unit making its use more flexible.

 

5. DISADVANTAGES

1. Split Package Unit: Split type is a split package unit and not a single package self-contained unit.

 2. While it is true that the Split System offers outstanding user conveniences, it is necessary to be aware of the disadvantages also. These can be counter-balanced by the following actions:

 • Usually a drop of 5-10% in capacity is observed in the split system due to the extended system tubing, when compared to that of the Window unit. This loss in efficiency would be compensated partially by selecting suitable sizes of the system tubes.

The other part of the loss can be taken care by increasing the air flow using four pole motor for the condenser fan resulting in lower discharge pressure.

 •  Split system has lot of joints. It is prone to refrigerant leakage. To avoid this problem, it is becoming a common practice to eliminate these joints by brazing the system tubes at the site. The unit is then evacuated and charged in the installed condition itself.

 

6. WINDOW AIR CONDITIONER Vs SPLIT- TYPE AIR CONDITIONER

Comparison of window air conditioner with split-type air conditioner is explained as follows: