Energy monitoring confirms- you need to have shell & tube condensers on your next chiller.

Considering a new chiller plant or chiller retrofit? Many modular water-chillers are focused on the lowest possible capital cost. This means cutting corners on parts that are critical to life span, maintenance, and long term energy efficiency of the chiller plant. In this example, an old modular chiller was replaced with a new ModulAIR chiller. This article focuses on long term energy efficiency using actual data to understand how the old chiller managed to consumed 300% more energy than the chiller that replaced it!

Comparison of energy consumption of old chiller vs. newly installed ModulAIR chiller.

Figure 1: Comparison of energy consumption of old chiller vs. newly installed ModulAIR chiller.

As you can see from Figure 1; the energy consumption of the existing chiller had become extremely poor, more than twice its original published kw / ton value. This graph is based on actual data recorded on site. Both chillers are operating at the same flow rates and temperatures for an equivalent comparison. The Figure also shows that the old chiller operates in distinct power consumption “steps” due to the on / off control nature of its scroll compressors.

 

Inside of a Brazed Plate condenser, passages are 1/8" wide.

Inside of a Brazed Plate condenser, passages are 1/8″ wide.

The existing chiller featured brazed plate condensers. Over time, debris from the condenser (cooling tower) system builds up in the small passages of the condenser. Despite multiple attempts to clean the condensers with specialized equipment and chemicals, the efficiency of the chiller continued to deteriorate. There is simply no proper way to clean the inside of a brazed plate condenser! To get this photo of the inside of a brazed plate condenser, we literally had to cut it open. Yes, this chiller had water-strainers too!

Image of a Shell & Tube condenser, passages are 3/4" wide.

Image of a Shell & Tube condenser, passages are 3/4″ wide.

Shell & tube condensers on the other hand, can be opened and cleaned on a regular basis. This helps maintain heat exchanger performance and prevent situations as shown in Figure 1. To learn more about different types of heat exchangers, see our other blog post.  The end-caps of the condenser can be removed and conventional cleaning equipment can be used to clean the tubes. All ModulAIR chillers feature shell & tube condensers as a standard offering. There is no need to add strainers which can become plugged up causing low flow issues and other maintenance headaches.

 

 

As discussed, the new chiller has significant improvements in terms of energy efficiency. This is party due to advancements in compressor technology and party due to having cleanable condensers that will not foul over time. Using measured data, the new chiller saves $22,000 in electricity every summer for this customer and was given incentives from the local government.

New ModulAIR chiller installation shown.

New ModulAIR chiller installation shown.

To learn more about the energy efficiency characteristics of the ModulAIR chiller manufactured by Advance Industrial Refrigeration, click here.

 

Posted in Modular Water Chillers

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