Posted by: @setithing

Hi,

Just to preface Mod's I hope this is the most aproprate area as most componets are GSHP related I though this would be better. Ever with the energy source being air or even storage too.

After getting my own place seeing the energy bills and loving a good engineeing project. I set about seeing how much of the heating energy I could get my self, I was aiming for self suffiency but have given into reality.

In research heating systems I came across this: https://elkement.wordpress.com/2016/01/07/how-does-it-work-the-heat-pump-system-that-is/

The idea is that the air has lots of energy but only when it is warm but not when it cold, so can you bridge that gap with some storage. This is where the ice storage comes in. Turning Water to ice contains quite a bit of energy ~90KWh per M3 the same as heating the water to 80C. It also happens that 0C is an ok input temp for a GSHP. If the storage can tie you over a few days when it's bellow zero then the next warmer day you can melt the ice and recharge the battery.

I am sure the system can work but as with anything it's the how and under what conditions. The main draw for me is that you can control where the energy is going and add/remove bit's if that don't work.

I think this will do as a starter that site has some great info on it. I've see people have installed these systems in Austria,Germany and Poland but haven't seen any UK one if anyone knows more please let me know. It's looking like it will be a DIY project at this rate.

I'll post more with my calulations and graphs seperately.

All the best

Setitihing

Hi Setithing,

The first thing that I would like to clarify, is that turning water into ice does not store energy, it actually removes energy from the water in the process of turning it into ice.

GSHP's are more efficient than ASHP's because they extract energy from the ground rather than the air, so that with a GSHP the energy source is at a reasonably constant 8C to 9C, even when the outside air temperature could be -10C or even -20C. If the energy source to a GSHP is at 0C it would be no more efficient than an ASHP when the outside air is at 0C.

One of the ideas I have been researching is to heat a reasonably large quantity of water (1000 litres or more), by using solar thermal panels. The water is heated during the daylight hours, with the energy being stored in a well insulated tank or tanks, for use later. The idea is to use the heat energy stored in the water, to preheat the air being drawn into an ASHP, so that the overall heat pump efficiency is improved.

In the UK we often get days when the outside air temperature increases to 10C during the day, but then falls to around 0C overnight. If the heat energy collected and stored in the water during the daytime, was then used to maintain the inlet air to an ASHP at 5C or above for at least part of the nighttime, then I feel that the overall system efficiency would be improved.

Obviously not everyone would have the space or inclination to have such a system, but there are some who may find such an arrangement useful and cost effective.

Thanks for the thoughs Derek, I amit I proberly need a bit of a reality check on this but the maths problems alown are worths it currently. The effiencey savings I can see is having a almost garenteed 0C heat source and as you say above 0C it's just an ASHP.

There is a small solar componet but really it's not worth it. I guess theres a small saving from not having a defrost cycle but again not that much of a saving. Oh and you could get a wopping ~90W (2.16KWh/day) of ground source to a 1.5M3 tank if you freeze it.

Have been running some calulation of extractable energy so far it's crude but interesting, it include solar and air heat. So far I would have had to use the storage once (though mild year) plus I haven't included some effency losses just asumed ssystem loss it 20%.

 I haven't though about using higher temps to store energy, too going to have to try and model that now. Has you research found anything? I just wonder if the sensible energy density is too low.

A few generic question if I may.

Are there any ways to test a heat loss calculation like the MCS one? e.g. use gas bill - boiler loss to compare year numbers.

What is an estimate over size for heatpump to -2.6 heat loss. Say 4Kw heat loss so 6Kw heatpump?

Regards,

Setithing