The Digital Scroll Compressor - Improved Capacity Control But Is There a Downside?

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The digital scroll compressor is a form of scroll compressor commonly used in commercial air conditioners. It uses an unloading mechanism to provide a form of capacity control.
In this video we will cover the digital scroll compressor and its pros and cons. In the next video of this series, we will cover the inverter scroll compressor for comparison.
The aim of these videos is to help HVAC engineers make more informed decisions when choosing air conditioning equipment.
Links to academic studies that plotted the efficiency of the digital scroll compressor:
docs.lib.purdue.edu/cgi/viewc...
docplayer.net/15274978-Develo...

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14 июл 2024

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Комментарии : 12

@bryananderson3787 8 дней назад

What would be the result/symptom if the solenoid were to get stuck in the open(unloading) position?

@jonwiersig5800 2 года назад

My swimming pool pump has an energy efficient two speed motor. When operating at the slower half speed, by the affinity laws, the flow drops in half (proportional to the speed change), but the power drop drops by a factor of eight (proportional to the speed change cubed). Why not use a two speed motor on the scroll compressor rather than the unloader?

@Ali_Alhamaly 3 года назад

Thanks for highlighting the efficiency loss with the reduced capacity of the digital scroll. This is the first time I encounter this, I really thought that digital scroll energy consumption at part load looks similar to a scroll driven by a VFD (inverter scroll) the real question is when we compare the energy consumption at part load for digital scrolls vs fixed scroll, which one is better? the fixed scroll has to turn on and off to modulate the capacity and there is the degradation loss which is the loss in efficiency due to the cycling of the compressor. how does the degradation loss compare with the digital scroll loss at part load>

@airchange255 3 года назад

Very good question Ali. After we cover the inverter compressor, we should make a video comparing the seasonal efficiency of each compressor type. It would largely depend on the setup of the fixed speed scroll unit. If it is not oversized and has a reasonable hysteresis band, then the amount of on/off cycling shouldn't be excessive. Further, if it is a multi-stage unit, then the startup degradation will be less significant. For example, during a low load scenario with a twin compressor setup, only one compressor that is half the overall capacity needs to cycle on/off. Whereas, a unit of the same capacity but with only one large compressor will have a greater startup surge. There are standards for seasonal efficiency calculations here in Australia. From memory, it recommends a degradation coefficient of 0.25 for a fixed speed compressor unit. Meaning that as the load approaches 0%, the unit loses 25% of its efficiency. This resulted in a single stage unit having about the same seasonal efficiency as the digital scroll unit. But when multiple stages were added, the fixed speed unit was more efficient.

@Ali_Alhamaly 3 года назад

@@airchange255 Thanks for the details, waiting for your SEER comparison between all types. and would like also to have an IEER comparison if possible. IEER would be more suitable for large compressors suited for commercial application (larger than 19 kW)

@sukruozturk6758 2 года назад

Türkçe

@fuzzypickle5307 Год назад

Curious about the actual energy usage difference between the two, ive seen other sources go a little more in depth and state that the energy usage is nearly as efficient as a modulating compressor. We have to take into account LRA with the on/off cycle.