29, Mar 2014 / rebound


Greetings from the new guy! It has been a great first few months with Kevin and Russell, diving right in to development. As is appropriate for a startup, I’ve done everything from designing custom components to furniture shopping.

We kicked things off by redesigning IcePoint to use only fluids already in use for supermarket refrigeration. It feels good to stop continually Googling corrosion properties!

CSU’s Energy Institute completed our lab facilities. I was briefly disappointed that I missed out on the garage lab stage and the associated street cred (…in certain circles…) but with this kind of world-class space I got over it quickly.

To inaugurate the space, we designed a round of component testing to begin imminently. The bill of materials looks a bit different than the Russell’s first prototype system, with fewer vacuum cleaners rescued from the trash and more parts actually meeting specs.

As for those specs, the model wasn’t exactly set up to print out a shopping list. I developed models for many of the subcomponents to get us ready to build the 2kW prototype. The reasons IcePoint works so well certainly weren’t intuitive and this let me really dig into the system guts. After building subcomponent models to digest it one bite at a time, I have developed a much better sense of how the whole thing works together.

In developing a significantly more detailed INCIF model, and the direct contact chiller opposite it, we’ve recently learned about some unique thermodynamics. That second heat exchanger has a really unusual problem in thermal engineering- the heat transfer is too high (for you engineers: the heat transfer is very high relative to the mass transfer rate through a heat exchanger with some unfortunate geometry constraints). In other words, because of other geometric constraints the system over-performs in some areas and underperforms in others. Luckily, it is every engineer’s dream for the boss to come by and say, “Hey, could you please make this system work less well?” Difficult to work with, expensive, and poorly characterized heat transfer oil? Ciao! Air is a great not-so-heat-transfery heat transfer fluid, so let’s use that.

The best part is that using air allows us to replace some of the complicated custom components surrounding this direct contact chiller with inexpensive, mundane, but effective alternatives like automotive heater cores. This brings us back to the one bite at a time mentality- system level learning is really difficult when you don’t understand the individual components well. Therefore, our initial objective is to show how well the cycle works. So, the cycle is the first bite.

Our next IcePoint update will give you a tour of the prototype system, complete with a simple heater core using air. We’ll also continue working on a custom INCIF in parallel because, ultimately, we know a system with heat transfer this high has potential. But for now, we’ll keep proving the technology, one bite at a time.


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