how to improve self-constructed calorimeter (heat insulation)

Purpose:
My purpose of this project is to use some environmental friendly material to construct calorimeter instead of using styrofoam.


I tried:
I use two different size test tube as my calorimeter(as in picture).
And I tried two ways to improve heat insulation:
1.vacuum
2.silvered
But, these are not good enough to prevent heat loss.


Question:
1.Is there any suggestions to improve heat insulation.
2.Increase the space between two test tube would sufficiently prevent heat loss?


[![vacuum the space between tubes](https://i.stack.imgur.com/HFKVj.jpg)](https://i.stack.imgur.com/HFKVj.jpg)


[![silvered test tube](https://i.stack.imgur.com/MOnVj.jpg)](https://i.stack.imgur.com/MOnVj.jpg)





> 
> 1.Is there any suggestions to improve heat insulation.
> 
> 
> 


There are two issues to address: the heat capacity of the calorimeter, and the insulation of the calorimeter. There are several papers in Journal of Chemical Education about replacing Styrofoam cups with something as cheap and convenient and safe while improving sustainability (search for "[coffee cup calorimeter](https://pubs.acs.org/action/doSearch?SeriesKey=jceda8&AllField=coffee%20cup%20calorimeter)").


In a [lab](https://chem.libretexts.org/Sandboxes/Team%3A_Westfield_State_College/General_Chemistry_Labs%2C_Westfield_State/Calorimetry_lab) we recently did with students, we gave them bubble wrap, cotton balls, two-walled paper cups and a plastic cup (as insert, so everyone had the same chemical and thermal properties for the part touching the reaction mixture). The lab manual mentions some of the considerations.


In the photo below, you see the plastic cup wrapped in bubble wrap in a larger container, with the fitted foam lid in the background (which allows to insert the metal probe of a digital thermometer). I'm sure a couple of rounds of optimization wouldn't hurt for the design, but it is already a working model.


[![enter image description here](https://i.stack.imgur.com/jx9dEm.jpg)](https://i.stack.imgur.com/jx9dEm.jpg)


Looking at photos posted in the question, I would guess the biggest leak in the OP's design is at the top (convection of the air). An infrared thermometer with a small focal area makes it easy to investigate the points of heat loss. I would guess that the inner test tube has a fairly high heat capacity (roughly proportional to its mass). The Styrofoam efficiently creates small air compartments to insulate (little convection, little conduction) while having minimal heat capacity. You can correct for the effective heat capacity of the calorimeter if you characterize it carefully (either before the actual experiment, or by recording and analyzing a temperature trace), but if it is negligible, you save that complication. Many modern calorimeters work in an isothermal mode, where heat capacity and insulation become less critical.


A Dewar or any vacuum layer comes along with safety issues that should be considered carefully. The same goes for the flammability and chemical compatibility of the materials used for any design.



> 
> 2.Increase the space between two test tube would sufficiently prevent heat loss?
> 
> 
> 


If the space is too big and contains gas, you allow convection currents. The Styrofoam is closed-cell, so it does not allow for convection over large distances. I think the key for optimization is to measure the heat capacity and the heat flow in your current designs. Otherwise, you don't know what aspect to optimize.


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