Intelligent Defrost in Walk-in Freezers

Blog, Imperial Ideas, Recommended Reading, Cooler Cooler Solutions, News – October 1 2015

Walk-in freezers benefit from technology that includes intelligent defrost, cycling when necessary to save energy and money.


Have you ever sat back and thought about how much technology has permeated into our lives? Microchips and microprocessors are everywhere. Not only are they in our computers, but they are also now in our phones, cars, TV’s, stereo’s guitars, appliances, and the list goes on and on. What’s pretty cool about microchips and microprocessors is that they really do make a lot of what we do more efficient.   

In my opinion, efficiency, especially when it comes to energy efficiency, is good thing. Not only does it save us money, but it also helps conserve our non-renewable resources. Over the past few years, we have seen growth in microprocessors in refrigeration equipment within the foodservice industry. Where this technology really saves us money is through the use of intelligent defrost systems.  

Walk-in freezer needs defrost

I remember my mom defrosting our freezer when I was a kid, it usually entailed a screwdriver, chisel, hair dryer and some choice words at times. Fortunately, she didn’t work in the food service industry because she would really get bent out of shape with some of the ice I’ve seen in freezers.   

For defrosting an evaporator, standard mechanical equipment typically uses a time clock that a contractor sets for 4 defrosts per day. When the time that is set on the clock comes around, the system goes into defrost whether it needs to or not. Likewise, if the evaporator ices up between defrosts, which makes the system inefficient and uses more electricity, it’s not going to do anything until the time clock instructs it to. It’s a simple system and works well most of the time, like my 1970 VW bug but it’s not the most efficient vehicle on the road.
Conventional Defrost
Standard Mechanical Defrost

By adding a microprocessor and some sensors and transducers (I don’t really know what a transducer is but it’s a cool word), some smart engineers have been able to use multiple inputs to sense frost build up on an evaporator and determine when the time is right for going into a defrost. The net result of this is usually a reduction in the number of defrosts per day. With our typical electric defrost evaporators; anytime the heaters are not on the system is saving money.  
Intelligent Defrost
Intelligent Defrost

What I described above is typically called demand defrost, meaning the system is only going to defrost when required at any time of day or night. There are lots of these types of controls on the market now, which is definitely a benefit to owners and operators of commercial kitchens. I think this technology is pretty cool, it reminds me of my Honda Accord, it’s a solid car, saves me gas money over my Bug, has power windows, seats, AND the windshield defroster works all the time.   
Walk-in freezer intelligent defrost circuit board and microprocessor
Now imagine taking that demand defrost system and upgrading it a little more. So now you build into the microprocessor the ability to learn how the freezer is used over time and how much ice forms on the evaporator and at what times. Then you add the ability to block out times when you don’t want the system to go into defrost (delivery times, breakfast, lunch or dinner rush) and you have what one refrigeration manufacturer, Heatcraft, has coined “Smart” Defrost.   

For example, say you don’t want to go into defrost during the lunch rush between 11am and 2pm. The system will analyze how much ice is built up on the evaporator at a given time before 11am and then determine based on previous usage, if it can operates efficiently until 2pm without going into defrost. If the answer is yes, it will function as normal until 2pm and then analyze itself again. If the answer is no, the system will go into defrost at that given time and will be good to go during the lunch rush.   

To me, that’s a great feature. I really don’t want my system going into defrost (turning on the heaters and warming up the box) when people are going in & out of it a lot adding more heat through infiltration. So, by analyzing box usage over time and ice buildup, the Smart Defrost capabilities of the Heatcraft product line is like my mom’s new Cadillac. It’s a solid car, adjusts the seats automatically your settings when you put in the key, dims the rearview mirror when a car pulls up behind you, has front and rear sensors warning you if you’re getting to close to something and has automatic temperature control as well as heated and cooled seats, pretty fancy stuff.

So to summarize, as computers and microprocessors are becoming more common place in our lives, foodservice refrigeration manufacturers are integrating some really cool features into our refrigeration systems. Intelligent defrost is but one of the many changes refrigeration is going through to make it more energy efficient. We will definitely begin to see more and more of this happening as the technology matures.

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