RCCD stand for Refrigeration Capacity Control Device. It is a compact device comprised of hot gas bypass valve (HGBV), liquid injection valve, and a proprietary mixing chamber that eliminates the risk of compressor liquid slugging.
Why use RCCD?
Because ALL air conditioners are sized to be sufficient in the hottest weather. The rest of the year theywork with reduced efficiency, and with high cycling rate, which has significant disadvantages.
Benefits of installing RCCD:
- Improved humidity control during mid-season.
- Reduced cycling rate of the compressor.
- Increase in the efficiency of the compressor.
- Eliminates the risk of evaporator coil freezing.
How does it work?
Hot gas bypass valve (HGBV) senses the suction pressure, and automatically bypasses the right amount of hot gas to prevent low side pressure drops below the pre-set value. This in turn will maintain the evaporator temperature at the optimal set point for dehumidification, and of course completely eliminate possibility of evaporator freezing.
Why not use only the HGBV then? Because constant recirculation of hot gas would keep increasing the temperature of the recirculated gas, by adding the heat picked up from the compressor motor. This would lead to oil degradation, and catastrophic failure of the compressor.
Manufacturers of HGBV recommend piping the bypassed gas to the intake of the evaporator coil. This requires adding the 3rd line to split systems, and dumps the excess heat into the conditioned space. It also increases the amount of gas entering the evaporator, and reduces the efficiency of heat exchange in the evaporator due to uneven liquid distribution through the evaporator branches.
Enter the liquid injection valve. If hot gas is bypassed directly to the suction of the compressor all we need is a small portion of the liquid refrigerant from the exit of the condensing coil, to bring the temperature of the suction to normal levels. This process does not exchange any heat with the environment, but simply utilizes excess liquid that is available at reduced system loads.
This sounds good in theory, but the risk of liquid slugging is greatly increased, because the liquid needs time and space to evaporate, and remove heat from the bypassed hot gas.
RCCD mixing chamber is the solution for this problem. It consists of custom designed mixing nozzle followed by proprietary media that significantly increases the rate of mixing of liquid and gas stages, evaporation of the liquid and equalization of temperature. It also features tapered bottom mounted output port that guarantees by design that no oil trapping can occur in the mixing chamber.
- RCCD is economical and convenient device that addresses a major problem in common air conditioners that are built without any means of capacity modulation other than harsh On-Off cycling.
- RCCD mounts entirely in the condensing unit, with just 3 tubing connections.
- RCCD is factory pre-adjusted for most common requirements, but it can be fine-tuned in the field to optimize system behavior, or to meet varying customer preferences.
- RCCD requires no maintenance.