EKC 394 Chemical Engineering Laboratory II Thermal Conductivity of Insulating Powders

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Questions and Answers

What is the main objective of the Thermal Conductivity of Insulating Powders experiment?

To determine the electrical conductivity of several insulating powders

To evaluate the effect of temperature on the thermal conductivity of materials (correct)

To measure the specific heat capacity of insulating powders

To determine the thermal conductivity of different metals

What is the purpose of the 200 W cartridge heater in the test module?

To provide the heating source for the insulating powders (correct)

To control the power supply to the test module

To monitor the temperature of the insulating powders

To measure the thermal conductivity of insulating powders

What material are the test modules fabricated from?

Aluminum

Brass

Copper

Stainless steel (correct)

What does each test module of the Thermal Conductivity of Insulating Powders Unit contain?

At least 100g of insulating powders Signup and view all the answers

What does the power control circuit provide in the Thermal Conductivity of Insulating Powders Unit?

A continuously variable electrical output of 0 to 200 Watts Signup and view all the answers

What does the instrumentation provided for the test module permit?

Accurate measurement of temperature and power supply Signup and view all the answers

What is the purpose of the thermocouple in the heater?

To prevent the heating element from burning out Signup and view all the answers

Which materials have very low thermal conductivity?

Kaolin and magnesium oxide Signup and view all the answers

What is the purpose of utilizing thermal insulators?

To reduce heat losses from a hot body to the atmosphere Signup and view all the answers

What are the dimensions of the inner cylinder of the test module?

I.D. = 9.9 mm, Thickness = 3 mm, Length = 175 mm Signup and view all the answers

What is the sheath of the thermocouples made of?

Fiber glass Signup and view all the answers

What is the function of the power transducer in the control panel?

To measure the heat input to the heater element Signup and view all the answers

What does 'q' represent in the heat flow equation q   k A dT / dx   k ( 2  r x 1) dT / dr ?

Heat flow through a small element at any radius r Signup and view all the answers

What is the formula for determining the conductivity of the material in terms of q, r1, r2, T1, and T2?

$k q ln (r1 / r2) / 2  T1  T2 $ Signup and view all the answers

'ln' in the formula for determining conductivity represents:

$logarithm$ Signup and view all the answers

'Thermal conductivity' refers to the ability of a material to:

$pass heat through it efficiently$ Signup and view all the answers

Study Notes

Experiment Objectives

Main objective: Measure thermal conductivity of insulating powders.

Equipment and Materials

200 W cartridge heater provides a consistent heating source for testing thermal conductivity.
Test modules are fabricated from durable, heat-resistant materials designed for thermal experiments.
Each test module contains insulating powders and thermocouples for accurate temperature readings.

Power and Control Systems

Power control circuit regulates the amount of heat supplied to the insulating materials.
Instrumentation allows for real-time monitoring of temperature changes and heat flow within the test module.

Thermocouples and Measurements

Thermocouple in the heater measures temperature to ensure effective monitoring and control of heating.
Low thermal conductivity materials include aerogels, fiberglass, and certain types of foam.

Purpose of Thermal Insulators

Utilization of thermal insulators reduces heat transfer, improving efficiency in various applications.

Test Module Specifications

Inner cylinder dimensions: designed to accommodate the materials and maintain consistent thermal conditions.

Thermocouple Design

Sheath of thermocouples made from materials resistant to high temperatures and corrosion.

Control Panel Functions

Power transducer in the control panel converts electrical power into a readable format for monitoring.

Heat Flow Equation

In the equation q = -k A dT/dx = -k (2πr x1) dT/dr, 'q' represents the heat transfer rate through the material.
Formula for determining conductivity: k = q / (A * dT/dx).

Logarithmic Representation

'ln' in the conductivity formula denotes the natural logarithm, essential for calculating thermal resistance.

Definition of Thermal Conductivity

Thermal conductivity refers to the ability of a material to conduct heat through it.

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Description

This quiz covers the determination of the thermal conductivity of insulating powders such as kaolin, magnesium oxide, and mica, along with an evaluation of the effect of temperature on the thermal conductivity of materials.