View Single Post

12-28-2010, 11:14 PM
 Jetijs Gold Member Join Date: Aug 2007 Posts: 2,134
Hi bugler.
Look at this picture:
http://www.emuprim.lv/jetijs/plog-co...m/zupa-006.jpg

there you can see the cut slots in the bricks that house the coils. They are cut in the following configuration:

Yes, you can use single phase current and 2kW of power should be enough for about 20 liter reactor container. You can use either one heating element rated for 2kW or two 1kW ones in parallel. The voltage used is mains power so 220v in Europe and 110v in US. I don't know exactly the specs of the nichrome wire, but something around 1-1.5mm diameter wire should be used, you just need to get such a wire and measure the resistance of it for say a meter, then based on your power needs, you calculate the total length of the wire. For example, if the wire has say 30 Ohms of resistance per meter and you need it to work at 1000w of power, then at 220 volts that would be 4.54 Amps, so you need to get the wire so long that its resistance will limit the current to 4.54A. So if the resistance per meter is 30 Ohms, then at 220 volts 7.33A of current will flow through that wire, that means 1.6kW, that is too much, in order to get 1kW of power we need to increase the wire length till the total resistance of the wire is 48 Ohms, that then would be around 1.6 meters of wire. Hope this helps.

Here is how the electrical circuit would look like in your case of single phase current:

I use digital temperature controller, you can get them on ebay for about 40\$, something like this:

The relays are of solid state type, like this:

These are about 15\$ a piece. The temperature controller monitors the temperature in the reactor and sends 12v impulses to the bottom contacts of the solid state relays that turns them on and off so that the needed temperature is maintained.
A thermocouple is a temperature sensor, this is the thing from where the temperature controller gets the data from, it is a small metal piece with two wires coming out of it, the metal piece is put where the temperature needs to be monitored and the wires are connected to the temperature controller. It looks something like this: