tools, materials & knowledge for model makers
I thought I should look at the boiler heat loss versus published data. Although my test object is just a short length of copper pipe, it does represent a copper pipe. So, I went searching for some data and there is a table of data on the Engineering Toolbox (Ref 1). This data is really … Read more
The cooling curve and heat output of the Unclad versus Maximum Insulation boiler are compared. Previously we looked at the repeatability of the cooling curves and the known parameters for the boiler test object. Now, using the simple model that we discussed we can estimate the heat output of the test object versus temperature. The … Read more
Before starting the simple modelling I think it is worth looking at the known parameters for the boiler test object. From these there will be some simple assumptions and estimations. Assumptions Lumped point mass. Single temperature measurement represents the temperature of the object. Heat capacity does not change with temperature. Local air temperature represents ambient … Read more
Before going too far with the calculations I needed an initial check on the boiler test object repeatability. All of the data analysis will end up informing the insulation of the Burrell traction engine boiler. This initial look at the data will give me an initial feeling as to whether the data is good. Test … Read more
Looking at the thermal insulation of a boiler and just how thin I could make an insulator I started looking at Multi-Layer Insulation or MLI’s. The effective thermal conductivity of an MLI is in the order of 10-5 Wm-1K-1 as given by Sutheesh and Chollackal [ref 1]. The thermal insulation I achieved for the vertical boiler … Read more
After a few measurements on the vertical boiler, using the cooling curve to estimate heat loss, I achieved a reasonable level of thermal insulation. However, can I turn this into a more methodical approach in the home workshop? I can electrically heat a block of metal, it would be best if this was copper. Copper would … Read more
The saddle and the Burrell boiler have been on the bench for a while. Most of the delay was down to me struggling with the design and location of the steam valve. The Saddle The saddle was designed to allow me to split the cylinder and ports to make it all easier to make. This … Read more
Burrell Smokebox door curvature or no curvature? This miniature traction engine sits on my desk in various stages of design and build. Sometimes loving it and sometimes tormenting me. At the moment the smokebox door is staring at me with it’s flatness. It really does need to have some curvature. However, what is the curvature? … Read more
A few silver solder coupon tests to look at options for soldering copper and phosphor bronze (PB). The test parts are a representation of the PB saddle and copper boiler on the miniature traction engine. Preparing Test Parts Fundamentally a sheet of copper 1.2mm thick has a PB M4 bolt through the top and into … Read more
All the time I’ve been making the cylinder and saddle I’ve been concerned with the Burrell steam valve. How do I control the steam? I think I have three options: Make a valve part of the saddle Fit a standard steam valve to the side of the saddle Fit remote standard valve and run pipes back … Read more