Functional Requirements

• Around 300W of power usage

• Heat up the chamber to 70℃ 

• Off-the-shelf complete heater

• Compact due to size constraints

• Mountable on any surface or wall

The Stergo Fan Heater was selected for its power usage of 300 W, operation range of -45℃ to 70℃, and price point of $154. Alternative heaters cost more and failed to operate at the desired temperatures, making the Stergo Fan Heater the best choice.

Functional Requirements

• Operate between -15℃ to 70℃

• Non-flammable

• Under 1in thick

• R-value high enough for internal temperature at 70℃ when external at worst of -15℃

Polyisocyanurate was the final insulation selection after sponsor suggestion. Aside from its widespread use in industry, it renders the highest max temperature resistance from all the materials considered, fulfills the desired R-value requirement at 5.7, and is within the thickness allowance at 1inch.

Functional Requirements

• AC control board

• Durable and insensitive to vibrations

• Compact due to size constraints of the chamber

• Operate at temperatures up to or above 70℃

• Passive cooling

• Throughput of 300 Watt

The SSRK-240D20 relay was selected since it is a rail-mount, operates around the desired 70℃, has an integrated heat sink for passive cooling,and costs approximately $62. A control board was chosen that is compatible with the relay and our system. The Azteeg X5 GT control board allows for the use G-code, is bug free, SD card supported, and does not require a board communication.

Functional Requirements

• Accurate within 1 ℃

• Durable/rugged 

• 50mm length, 15 mm cartridge length and 3 mm cartridge diameter

• -15 to 50 ℃ operating temperature range

The thermistor was already implemented into other parts of the system by the company sponsor, and fulfilled all of the functional requirements outlined. Using the same thermistor reduced costs and system complexity.

Comparison of environmental control system with no insulation, the insulation used for initial testing, and final design.