It’s best to shut down units in multiple chiller plants when full load is not required – TRUE OR FALSE?
As misbeliefs can become common, and in time, can easily sediment in peoples’ mind, here at Daikin we are committed to put our expertise and knowledge at the service of the people of the sector. All this, with the aim to bring them value and help them make informed decisions when working on commercial heating, cooling and ventilation (HVAC) projects. This is what ANSWERING MISBELIEFS really is – a series of articles breaking downs false myths.
So, among the different myths in (HVAC), there seems to be is a lot of information about multiple chiller plants and how to manage them effectively. We all know when it comes to big buildings chiller plants may have installed different units working together to reach the cooling capacity target needed to satisfy the cooling needs of that building.
But while multiple chiller plants can more easily achieve high cooling capacity targets, energy efficiency is still an aspect that needs to be considered, as it both impacts the environmentally friendliness of the building and the operative costs that building owners have to bear.
Many in the industry believe that the best way to run a multiple chiller plant is to shut down part of the units when full load is not required, instead of running all the units in part load.
So, in case of multiple chiller installation, many consider shutting down chillers (and the related pumps) as the load decreases, the best way to go to get maximum energy efficiency when full load is not required.
Is that TRUE or FALSE?
Well, the answer is false.
With Inverter, thanks to the high efficiency in part load operation, running all the chillers in the plant in part load (even if they have “fix-speed” pumps on primary circuits) can be more efficient than shutting down part of the chillers.
The Inverter or VDF (Variable Frequency Drive) is an electronic power component that, by varying the frequency of the motor power supply, modulates the compressor rotational speed (RPM) and in such a way, controls the compressor capacity.
Read more here about the benefits of using inverter technology
This technology is recognized being responsible for helping chillers and heat pumps delivering great efficiency performances, especially when it comes to part load efficiency.
This technology can become crucial also for multiple chillers applications, not only ensuring greater energy efficiency levels and lower operating costs, but also lower maintenance costs and quick Return on the Investment (ROI).
Read more here about why part load efficiency is important
Here is an example!
Let’s consider the case of a Hotel. This kind of application is a particularly relevant example, since hotels’ load typically vary depending on the season, or in case of particular events, but also because during this pandemic they can’t operate at full capacity.
Read more here about HVAC systems for hotels
The hotel we are taking as an example is based in Dubai and requires 2MW of cooling capacity at 46° C design ambient conditions. Considering that the multiple chiller plant (Fix speed pump on Primary plant) would run 8,760 hours per year and the cost of electricity would be 0.11 €/kW, here is how Inverter chillers would compare to non-Inverter chillers.
|Location||Seasonal efficiency||Savings on operating costs||ROI|
|Dubai||24% higher||24,220 EUR/year||13 months|
Relying on controls to sequence the chillers in the plant
When the HVAC project requires to split the load across multiple units of different sizes, it is often useful to rely on smart solutions that can help control the chillers as they were one big single unit.
The Daikin Intelligent Chiller Manager (iCM), for instance, is one of those smart solutions. It is a tool designed to control, sequence and optimize the performance of multiple chillers, and is the perfect solution for this type of plants. The iCM, in fact, harmonizes the way every single chiller in the plant operates, allowing them to reach their goal with minimum effort, both in terms of energy consumption and mechanically. All this with a positive impact on chillers’ durability and efficiency.
Are you working on a project requiring a highly efficient multiple chiller plant? Then, get in touch with the form below!