Over the past few years, compressor manufacturers have worked to develop modulation technologies that not only provide better system performance, higher efficiency, and improved comfort but also meet specific part- and full-load challenges.
One of these technologies is the moduload capacity control for 3D compressors. In short, this technology can adjust the capacity of the compressor according to certain applications and varying system loads. In order to understand the benefits of moduload capacity control, let’s take a closer look at this technology and the key challenges it can address.
Assessing the Underlying Issues
In many air conditioning and refrigeration applications, system loads typically vary over a wide range, according to weather conditions, building occupancy, lighting, and activities.
Because full system capacity is not always needed, the compressor should ideally reduce its output under light load conditions. This can be done by making the compressor run intermittently or reducing its capacity according to load requirements. In addition to consuming more energy, frequent cycling will eventually lead to excessive wear and tear, followed by premature compressor failure. As a result, a compressor equipped with a means of modulating its capacity to match system loads is typically the preferred choice in most commercial and industrial applications.
To reduce capacity in a regular compressor, one or more cylinders become inactive temporarily during unloading. For example, in a four-cylinder compressor, only two or three cylinders will continue to operate. Although unloading the compressor will reduce its capacity, the problem with this method is that it cannot precisely match the capacity of the compressor with the load.
Considering this issue, the development of new technologies has become critical to ensuring optimum system control and performance. Some of the technologies that can be used to adjust compressor capacity to match load demand include the variable frequency drive, inverter scroll technology, digital scroll technology, discharge bypass, and the most efficient one: the moduload capacity control for 3D compressors.
How Moduload Capacity Control Technology Works
In a 3D compressor equipped with moduload capacity control, the compressed gas is transferred from cylinders into the storage chambers during unloading. On the suction stroke, the gas re-expands into cylinders, reducing the capacity of the compressor.
As most of the energy consumed during compression is recovered during re-expansion, a 3D compressor with moduload capacity control can deliver higher efficiency in low-, medium- and high-temperature applications. Additionally, because all cylinders are unloaded at the same rate, moduload capacity control ensures a smooth, well-balanced compressor operation in the unloaded mode.
Coming down to benefits, load matching is by far the greatest advantage of the moduload capacity control technology. In a nutshell, this technology allows systems to deliver the precise amount of cooling or heating needed for unique applications, including applications that focus on full- and part-load efficiencies.
In areas where we have different loads at different times of day, such as classrooms, conference rooms, restaurants, and kitchens, having a system that can keep up with changing loads will provide enhanced comfort for building occupants, irrespective of weather conditions and daily activities.
Furthermore, when temperatures are precisely controlled, the compressor will run for extended periods of time. Longer run times will translate into reduced humidity levels and lower energy bills.
Last but not least, the moduload capacity control technology ensures compliance with the latest ASHRAE standards for part-load (IEER/IPLV), full-load (EER) and seasonal efficiencies (SEER/HSPF).
For more information about the compressor technologies that can make air conditioning, HVAC and refrigeration systems more efficient, please check back on a regular basis!
