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Catalogue Flexible Heaters Design Guide

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Designing with Thermofoil Heaters

Conducting experiments

Heat transfer theory is complex. It's usually best to prototype your system with actual heaters to observe behavior and fine-tune the design. Minco offers a variety of tools to help you:

Design Kit: The Flexible heaters Prototype Design Kit (part number TB-H1) allows you to easily test and prototype a heating concept before starting on a journey of custom-built-to-order product.

Filled with flexible Thermofoil heaters, instructions and technical data, this kit will help you move towards successfully integrating flexible heaters into your application. Learn more at www.minco.com/heaterkit/.

Variable power source: An Ac power supply ("Variac"), power resistor, or rheostat lets you test different power levels across the heater or zone by zone.

Temperature sensor(s): A small Thermal-Ribbon RTD such as model S665 is easy to move and reapply to test temperature in various locations. See sensor options in the "Sensors, Controllers & Accessories" section.

Controller: Models CT325, CT15, and CT16A cover the range from simple to sophisticated design for testing control schemes. See controller options in the "Sensors, Controllers & Accessories" section.

Estimating power requirements

The total amount of power required for an application is the larger of two values:

1. Warm-up power + Heat lost during warm-up

2. Process heat + Heat lost in steady state

Warm-up power: Watts required to bring an object to temperature in a given time. The basic formula is:

, \ mC_p (T_f - T )

P(watts)=-^-^

where:

m = Mass of object (g) C_p = Specific heat of material (J/g/°C) T_f = Final temperature of object (°C) T = Initial temperature of object (°C) t = Warm-up time (seconds)


Material	Specific heat (J/g/°C)	Density (g/cm³)
Air	1.00	0.0012
Aluminum	0.88	2.71
Copper	0.38	8.97
Glass	0.75	2.64
Oil (typical)	1.90	0.90
Plastic (typical)	1.25	Varies
Silicon	0.71	2.32
Solder	0.19	8.65
Steel	0.50	7.85
Water	4.19	1.00

A mosaic of standard heaters, with dual industrial power supplies, helps to determine edge profiling for uniform temperature.

For other materials see Minco white paper "Estimating Power Requirements for Etched-foil Heaters" at www.minco.com/e2e

To get: Multiply: J/g/°C BTU/lb/°F X 4.19 g/cm³ lbs/ft³ X 0.016

Process heat: Heat required to process a material when the heater is performing useful work. The formula above also applies here, but must also include latent heat if material changes state (melts or evaporates).

Heat loss: All systems lose heat through convection (air or liquid movement), conduction through support structures, and thermal radiation.

White Papers

Download these helpful white papers to assist in designing and testing with Thermofoil heaters:

• Estimating Power Requirements for Etched-Foil Heaters

• Prototyping Techniques for Etched-Foil Heaters Both available at: www.minco.com/e2e

inner element outer element

power supply power supply

The resulting custom heater looks like this.

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