Capacity from 10%-100% results in an unmatched output from the Digital Scroll.
This wide capacity output is continuous and seamless and is an improvement over the inverter technology, where capacity outputs can only be achieved in steps. The seamless delivery of capacity also ensures that there is a very tight control on room air temperature.
A wide capacity output also contributes to high seasonal energy efficiency of the system. Frequent start-stops of the compressor consume more energy. Wider capacity output of the Digital Scroll reduces the number of start-stops.
High Seasonal Energy Efficiency
For modulated systems, single point efficiency is not the right gauge when measuring the efficiency of the system. The seasonal energy efficiency ratio (SEER) has to be calculated to get a good idea of the savings from operating the system year-round.
The Digital Scroll performance has been evaluated as per JIS & ARI standard and showed excellent SEER. The SEER advantage becomes even greater for a tandem configuration – a Digital Scroll compressor in tandem with a fixed speed compressor. At full load capacity, when both compressors are operating, the system has a high EER and at 50% capacity, when only one compressor is operating at full load, the system operates at high EER also.
Oil return is a major issue in variable capacity multiple evaporator systems. Current technologies use an oil separator and/or complicated oil return cycle to ensure oil return after some period of operation. The Digital Scroll is a unique compressor – it does not require an oil separator or an oil return cycle.
There are 2 factors that make the oil return easy. First, the oil leaves the compressor only during the loaded cycle. So at low capacities, very little oil leaves the compressor. Second, as explained before, the compressor operates at full capacity during the loaded cycle. The gas velocity in the loaded cycle is sufficient to return oil to the compressor. Our testing has shown that oil is able to return to the compressor even in the worst operating conditions – low modulation, 100 meter pipe length and 30 meter elevation (with standard oil traps), both straight and reverse elevation.
Dehumidification is necessary to ensure comfortable living and this becomes more important during low modulation operation. In the inverter system, at low modulation, the compressor operates at a lower frequency. This reduces the mass flow of refrigerant and results in a higher suction pressure. This results in a higher Sensible Heat Factor (SHF).
The Digital Scroll compressor provides very good dehumidification because it operates at a lower suction pressure than the inverter. As mentioned before, given any modulation output, the compressor operates at full capacity during the loaded part of the cycle. This full capacity operation results in a lower average suction pressure that leads to a lower SHF.
Electromagnetic Interference is a major issue in inverter-driven systems. In many countries, particularly Europe, there are strict regulations on the amount of electromagnetic interference that any device can emit.
The Digital Scroll system generates negligible electromagnetic interference because the loading and unloading of the Scrolls are mechanical operations.. This unique feature not only eliminates the need for expensive electromagnetic suppression electronics, but also adds to the reliability and simplicity of a digital system.
Quick pull down of room temperature and quick adjustment to demands are essential for customer comfort. Because Digital Scroll can provide transition from 100% capacity to 10% capacity or vise versa instantaneously by changing the loaded and unloaded cycle time, it can react much faster to the changes in system demand without having to pass through intermediate speed changes as required in the inverter systems.
Reliability of system and electronics is an issue in developing markets in Asia. In an inverter system, the electronics is typically complicated. Exposing this complex electronic system to uncertainties of installation and extreme weather conditions results in reliability issues.
The situation is made more complicated by using various bypasses – hot gas bypass and liquid bypass. We will discuss bypass shortly, but the bottom line is that complex systems have a higher probability of failure. The Digital Scroll system is fundamentally simple. Figure on the right shows the typical electronics for the outdoor unit controller.
Hot gas bypass and liquid bypass are used in most of the current technology options valuable. These protection devices are required because the compressor is not able to go down to very low capacities. The Digital Scroll can go down to as low as 10% capacity, so these bypasses are not required. This results in cost savings and system simplicity.
Smaller footprint leads to lower material cost, packaging, storage and shipping costs. Because of its simplicity, a Digital Scroll system can be designed in such a way that it can be more compact and the savings in space can be as much as 30% over present technology options.
