7. Thermal Control
Thermal Hardware Lab: Demonstration and Control of a Heater
Purpose
- Demonstrate and visualize heater functionality using a controlled power supply and battery board
- Retrieve, measure, and visualize temperature sensor data for solar panels and boards with lamp/light simulation
- Show how heat transfers through a primary structure
- Operate and extract measurements from thermal sensors
Required Materials & Setup
- Power Supply
- Power supply leads
- Satellite Structure with solar panels and antenna board attached
- Heater element
- Multimeter with leads
- Temperature gun
- Set of helping hands
- Cell phone and temperature application downloaded (1 suggestion provided in the steps below)
- Aluminum can
- String about 6-8 inches long or rubber band that will fit over an aluminum can or can utilize Kapton tape (aka space duct tape)
User Guide for Heater:
The entire line of products and specifications can be found at Kapton Heater: KHLVA-103/5. Below are the specifications that correspond with the heating element in the Artemis CubeSat kit
| Model No. | Width, in (cm) | Length, in (cm) | Total Wattage for Watt Density
5 W/in^2 |
| KHLVA-103/2 | 1 (2.54) | 3 (7.62) | 15 |
Although this specific heater is shown, this lab can be done with different Kapton Heaters. Depending on what you have, make sure to refer to the datasheet of the specific Kapton Heater that you will be using.
Procedure
Lab procedures are to be done in a temperature-controlled environment, AC, out of direct sunlight to minimize the effects of potential convection and radiation.
General Resistance Testing of the Heater Element
Setting the multimeter to ohms/resistance to measure the internal resistance of the heating element. This is a quick and easy test to be sure that there is not an open circuit within your heating element and that the resistance of a heating element correlates with the heater’s ability to transfer electrical power into heat.
It is irrelevant which lead goes to which wire when doing the resistance test. This step is easier if you have a buddy to hold one end of the wires while the other holds the leads. The resistance should be sound 57 ohms for a properly working heater image. If the reading is O.L or anything drastically higher than 57 ohms there may possibly be an open circuit or an improperly-working heater element. This specification can change from different models of heater elements. Be sure to always look up the specifications for the one you are using. Like in the previously provided information shown for the current element that will be being used.
Building the frame with Antenna Board Attached
You will need to build the frame again for this lab. Here is the documentation required if you need to refresh your frame-building skills: Structures: Assembly and Stress Lab
Installing solar panels
You will need:
- Assembled frame with the antenna board (the antenna is not necessary to attach)
- 4 solar panels
- 16 bolts for solar panels
- Driver for the bolts.
Start by taking one solar panel. It is irrelevant which one you choose. Just make sure it is lined up facing the correct way.
The side with the connectors will be towards the top of the CubeSat.
Four bolts will be needed for each side.
Do not over tighten the bolts or the solar panel will not lay flat. Lightly tighten the bolts just till the bolt is flush with the panels. Install all the bolts the same way before securing them to a hand tight torque. Repeat this process for all four sides.
Handling the Heater Element
- Do not touch with your bare hands
- Do not go over 28 Volts and/or 2 amps
Downloading Free Application for Thermal Imaging
An additional option to monitor the temperature change would be to utilize a free thermal app on your phone. The one we used in the video was “Night Vision”.
This is an inexpensive way to see the temperature changes on your heater element. This application is not completely accurate or overly sensitive, but it will allow seeing temperature differences.
Connecting the Power Source to the Heating Element
- You will need:
- Power supply
- Two leads for the power supply
- Thermal gun
- Heating element
- Two pieces of Kapton tape (aka duct tape of outer space)
- Optional thermal app for phone
- Cubesat structure with solar panels attached
- Provide links on how to construct from previous labs
Connect the leads to the heating element. Positive and negative are irrelevant for this experiment.
Plug the heating element into the power supply and tape the heating element to the solar panel on the opposite side of the antenna using two pieces of Kapton tape as seen below.
Next, set your power supply to 5 volts and .5 Amps
Next take your base temperature measurements on all 4 sides prior to turning the power supply on:
Repeat this process for about 10 minutes. Every minute take a reading on all of the sides and record the data. You should see an increase in temperature on the side with the heating element and will not see much of a difference on the adjacent and opposite sides.
Additionally, you can take thermal images with the previously mentioned portion of the lab with the can. Keep in mind that the free cell phone apps are not very advanced or sensitive but you may see a slight difference as the heating element gets to maximum heating ability.
Keep track of your results on a table similar to the following.
In the next part of this lab, you will just need the lamp (aka sun simulator) and the assembled CubeSat.
Take one measurement for your base measurement and record your findings for all four sides as you did in the previous step of this experiment.
Shine the lamp onto the CubeSat.
Take one measurement for each minute for 10 minutes and record your findings. Make sure you are taking the temp behind the magnifying glass or you will be recording the temp of the lamp and not the CubeSat. Your chart can be similar to the set up in the previous part of the experiment.
Take note that it may be a little more difficult to use the app in this step, but if you take it from behind the magnifying glass (the side closest to you) you will see a slight variation in temp. Make sure not to move the lamp when taking photos because you will be interrupting the function of your sun simulator.
