Frans Peeters November 30, 2006

Dewar CookerDewar (Thermos) Cooker

DEWAR pots are dual silvered glass pots under vacuum . No heat is lost !!!

CARELESS COOKING ! No vapor ! (vapor= 500 % more Kcal loss )No overcooking ! 1hour Cooking or 4 h cooking the cost is equal !!! Soya , rice, ......

Vegetables ,broccoli eo needs 1h at 85 ° C. at no surveillance .
It means ,now cooking is no yob ! Only preparation from garden to the pot .
Eating time may be variable ? when you open the pot ,and separate off the water .

Result >25 % heat saving

Equipement :

Dewar pot 1L / person 20 L for Africa
Heater 300 W / L Quarts Ni Cr
Termostat sensor inside 85 ° C. NTC 5KOHM
Solid state best Proportional regulator . Chip TCA 280 .
Model Grand Lux : long ax circulating pump 5-10 Watt .

This are my own tests ;not from a manufacturer !.( It is lab material ,liquid nitrogen container l used for high vacuum pumps for mass- spectro meters ).

TEST : We start from water ( vegetables included .) at 10 ° C. Heat it to 85 ° C only . delta =75 ° C .A duar keeps this heat for more then 3 h ! The real cooking ( means softening here !) needs no energy only “time at a temperature” !

Normal cooking 10°C to 100° C is delta 90 + heat loss to keep it at 100 °C + excess X5 in cal. to form annoying vapour ..

My own practical test shows >23 % energy saved in the delta 90/ 75 and internal heating / external only .( steam production from stupid cooks is not included . Even not the pot and heater radiation loss from ordinary cook pots .Even not the bottom bad heat transport.)

Depending the cooks notion of physics or stupid overcooking and inefficient stoves .+” taste of food ready “, the % saving can be much more !

The most interesting is : no vapour and no care is needed while it becomes weak to eat , at 85 ° C.

(For beans and manioc it must be investigated more .when the poison is destroyed by heat or temperature .).

(Also vitamin gain or loss .)

Test it your self . Delta temp . and volume gives heat capacity .
Heating time X watts = watthours. 1cal=4,2 watt sec

The glass is PYREX = borosilicate like all lab glass . The 20 liter model is used 15 years for liquid nitrogen at minus 196 ° C .

The cover 4 cm cork or polystyrene foam .or silicate foam + PE film .

A mixing pump is a perfection of my tests .against temp difference from top to bottom .

The dewar has a protection shield .for bumping ,not falling .

Mind your definition of cooking ! And food softening at 85 ° C .

The main energy is in delta t and rather none in keeping it with a dewar for 3 hours .

10 ° C temp drop if NOT heated for 3 hours .

So reset your mind on zero for what is,”food eatable and healthy “.

Cooking means making steam for noting !

Keep it for making etheric oils .

Hard food needs hydrating swelling not exploding the cells . .


Kevin Chishom:
Dewar Flasks are very common, known here as Thermos Bottles. 1 liter thermos
bottles are very common.

Andrew Heggie:
Invented by James Dewar, a scotsman. As I spend my working life outdoors I'm quite familiar with vacuum flasks, nowadays we use stainless steel ones and they are very effective. Put 6 ounces of Wheat in a thermos bottle, fill with boiling water in the evening Next morning, you have a very filling breakfast for less than $C0.10.

Sir James DewarNike KD 11