Microwaving dry wood.

[ericdockum]

Here, of course!

 

[chaoticbob]

The porridge problem is indeed tricky Eric, and quite possibly unsolvable. I had been thinking to suggest that measuring the temperatures of the two bowls when they emerged from the microwave might be a way forward - all other things being equal, your wife's bowl, having a smaller amount of porridge in it, should be the hotter. However, as you rightly point out, small variations in the composition of the bowls may defeat that approach. As far as I know, dielectrically matched 'his 'n' hers' porridge bowls are not currently available. That may change in time of course. We can only hope.

One Jiajun Fan has written at some length on the topic of microwave pyrolysis of cellulose here. Although his main interest is in using microwave radiation to break down cellulose/lignin into usable biofuels he finds, amongst many other other fascinating things, that the rate of temperature increase in microwave irradiated cellulose with 6% bound water is very much greater than in dry cellulose, which suggests that the bound water is pretty effective in absorbing microwaves. This is of course relevant to your more serious question - bound water in dried wood is held in cell walls by hydrogen bonding to cellulose as I understand it.
I look forward to reading the results of your experiments!
Regards, Rob.

 

[finneyb]

......One Jiajun Fan has written at some length on the topic of microwave pyrolysis of cellulose here. Although his main interest is in using microwave radiation to break down cellulose/lignin into usable biofuels he finds, amongst many other other fascinating things, .......Regards, Rob.

Page 15, last para of the erudite publication above shows Jiajun Fan to be a female of the species.

And as she has now finished her research there will be a spare microwave at the Department of Chemistry Sheffield University - perhaps a way forward is for Eric to use that after applying for a suitable grant from the Porridge Trust.

 

[Phil Pascoe]

When you're done drying your wood you could use your redundant microwave for this -
http://www.waynesthisandthat.com/Fracta ... icity.html

 

[finneyb]

When you're done drying your wood you could use your redundant microwave for this -
http://www.waynesthisandthat.com/Fracta ... icity.html

A guy was electrocuted in US recently doing this - I don't even like the results
https://www.usnews.com/news/best-states ... rt-process

Brian

 

[ericdockum]

Thanks for the link to the interesting paper. I will have to have a read in detail - who knew heating cellulose in a microwave could be so complex?

• My 1st major takeaway is that microwave heating starts the breakdown of cellulose 120c lower than simply heating it - 180c mentioned. Hence MW a bit of wood could cause changes and breakdown before you might expect it to happen.
  
  Nothing much seems to happen to the cellulose for cellulose /water mixes up to 100c, as the water absorbs the energy. Of course this is for intimate mixtures, not a lump of dry wood next to a bowl of porridge. The presence of the water will reduce the available energy for the heating the wood.
  
  So given a domestic MW power output, 800w for 3 1/2 min heating a dry wood item and a quantity of free water, all at atmospheric pressure, it might depend on if the wood will reach 180c before the time is up.

I will have a deeper read before going to the experimental phase.

I have seen the fractals thing a while ago, actually I quite like the effect, but the rig ups people suggest look so scary I will not be doing that. I don't like fractals so much I will give my life for them!

Thanks all for the input,
eric.

 

[AJB Temple]

This has been a brilliant thread. I had not previously considered a personal pie microwave for the workshop.

 

[John Brown]

Just resign yourself to eating the same recipe and amount as your wife. You know it makes sense...

 

[J-G]

I've just re-read this whole thread and have to say that the proper answer has been spectacularly avoided!

I also make porridge some mornings - NEVER in a microwave - what is the point? - ericdockum states that the microwave is on for 3m30s, mine takes about a minute to come to the boil and then has 3m on 'simmer'. The difference in the two servings seems to be just the amount so made properly (on the hob) the measured serving can simply be weighed and the unimportant serving can be whatever is left - no confusion about which bowl has the smaller amount in, it's never out of sight!

I use 45gm Oats, 200ml milk and 100ml water, a pinch of salt and a knob of butter are optional of course as is Strawberry (or other) Jam / Syrup / Honey.

 

[chaoticbob]

......One Jiajun Fan has written at some length on the topic of microwave pyrolysis of cellulose here. Although his main interest is in using microwave radiation to break down cellulose/lignin into usable biofuels he finds, amongst many other other fascinating things, .......Regards, Rob.

Page 15, last para of the erudite publication above shows Jiajun Fan to be a female of the species.

And as she has now finished her research there will be a spare microwave at the Department of Chemistry Sheffield University ........

My apologies to Jiajun Fan if she is reading this. In my defence I looked up the name Jiajun on Nameswiki before posting because I didn't want to fall into that all-too-common folly of assuming that microwaving wood was an exclusively male preserve, and read that Jiajun was 100% male as a 'first name'. But of course first and second names work differently in different cultures. Mea culpa. For the record, I think the work was done at York rather than Sheffield though? It might lead to confusion and consternation if Eric were to contact Chemistry at Sheffield asking if they had extended their cellulose pyrolysis experiments to include the influence of porridge!
Rob.