Why does Sunamp appear to be the only PCM based heating system?

[dnb]

Or are there others I've missed?  I would prefer not to discuss the issues of the Sunamp specifically - there are enough threads for this already.

 

It looks to me like there are any number of businesses around the place that make and sell PCMs of a whole range of temperatures. But there's only one product I've seen that makes use of them at  temperatures high enough for DHW. Is it particularly difficult? Or a very small niche market?  It has always (since my father-in-law showed me the PCM based freezer he built for his yacht many years ago) seemed to me that they could be a good idea if implemented wisely.

[Ferdinand]

Perhaps because it is new technology, and there are a number of recent Patents held by Sunamp protecting the system.

 

https://patents.justia.com/assignee/sunamp-limited

 

I would be interested to hear the story of the Phase Change Freezer.

F

[dnb]

@Ferdinand The phase change freezer was essentially the answer to "How do I eat steak followed by ice cream in the middle of the Atlantic, while transiting in a 34" wooden yacht?". My father on law was a very clever chap who had the knack of seeing the very simple and obvious solution to a problem that everyone else had missed. When I tell you how it worked, it will be so simple and obvious that it won't seem impressive. It would be fair to say a sizable number of his ideas have been incorporated into my house design. It's a real shame he never got to see the house other than in drawings.

 

The problem with sailing is getting power for use in "hotel services" as the RN call it. It was even worse in the early 90s when solar panels were expensive and pretty awful things. So you're limited to power sources like running an engine, towing an altenator etc to charge batteries (again, in the early 90s these weren't anything like we have now), so efficiency is key for long range sailing. He built a massively insulated top opening box with the best volume to surface area he could fit in the space, and pieced together a reverse carnot cycle freezer using parts such as an airconditioning compressor - because taking mechanical power from the engine was more efficient than driving an inverter. To minimise engine run time, he used a pair of aluminium plates with a "bag" filled with strong brine. The freezer oviously froze this in the cooling cycle, taking the box temperature to -20c or so, and it acted as a cold store for many days at a time provided the box wasn't opened much (and there's plenty of spare PCM sloshing around should the bag leak...). Thus engine runtime was minimised and used relatively efficiently (5 to 10 minutes every 3 days), there was no battery load imposed and he and the crew (a younger SWMBO) ate well. Simple solutions tend to work well. 

Edited November 7, 2020 by dnb