Comparative Study of Thermal Properties of Some Common Roofing Materials in Nigeria
Chapter One
Aim and Objectives
This research aims to measure and compare the thermal properties of some common roofing materials in building design in Nigeria.
The Objectives are;
- To identify common roofing materials used for buildings in Nigeria
- To measure and compare the specific heat capacity of these materials
- To measure and compare thermal conductivity as well as to evaluate thermal resistivity of the materials
- To measure and compare the thermal diffusivity of the material
- To measure and compare the thermal absorptivity of the material
CHAPTER TWO
REVIEW OF RELATED LITERATURE
THERMAL PROPERTIES OF ROOFING MATERIALS
The present research is focused on the thermal properties of common roofing materials for building design in Nigeria. In this chapter, these properties will be reviewed in detailed.
Thermal property is any characteristic of a material defining the substance and related to temperature dependent.(Isidioro Martinez, 2016)
THERMAL CONDUCTIVITY (k-value)
Thermal conductivity is defined as the quantity of heattransmitted through a unit thickness of materials in a direction as a result of temperature difference under steady state boundary condition. This implies that heat conduction occurs when a body is exposed to temperature gradient and becomes serious when different parts of a body experience differential temperature ratings. The consequence of that is the initiation of heat flow from the higher temperature region to the lower region. (Owate et al, 2007)
METHOD OF MEASURING THERMAL CONDUCTIVITY
There are a number of possibilities to measure thermal conductivity, each of them suitable for limited range of materials, depending on the thermal properties. In general there are two basic method of measuring thermal conductivity which are the steady – state method and non – steady- state method. (Bauer & Westfall, 2014)
STEADY‐STATE METHOD
Steady‐state method applies Fourier’s law of heat conduction to measure thermal conductivity (Yuksel, 2016).
The solution to the problems with the different steady heat‐flow method is to convert the heat transfer problem to a one‐dimensional problem, thus simplifying the mathematics. The calculations change for the models of an infinite slab, an infinite cylinder, or a sphere. The typical specimen geometry, the configuration of a measurement system, and the magnitude of the thermal conductivity are used to distinguish between different types of thermal Conductivity measurements. The thermal magnitude of the measuring object is determined by the following measuring techniques using the direction of the heat flow, the conservation of the heat flow, and an auxiliary layer having a known thermal property(Yuksel,2016).
CHAPTER THREE
MATERIALS AND METHODS
This chapter summarizes the techniques used in carrying out the measurement of thermal properties of three different samples of roofing materials (Zinc, Aluminium coated and stone coated steel).
Materials
Materials used to carry out this research work are:
- Resistor
- Ammeter (Micro ammeter)
- Voltmeter (Milli voltmeter)
- Alligator clip
- Vernier calliper
- Micro meter screw gauge
- Power supply
- Wires
- Three different roofing materials
- Thermometer
- Calorimeter
- Weigh balance /beam balance
- Heater
- Insulating jacket
- Beaker
CHAPTER FOUR
RESULTS AND DISCUSSION
The results obtained from experiments are presented in this chapter. The results are presented in tabular form .Graphical analysis is done and discussed accordingly.
CHAPTER FIVE
SUMMARY, CONCLUSION, AND RECOMMENDATION
SUMMARY
In this research work, thermal properties of three different roofing materials were compared in Nigeria. With the combination of Ohms law and Franz Weidman principle were used to obtained the electrical resistance, alongside with the measured dimensions, the parameter were used to compute the electrical resistivity and electrical conductivity of the sample. With temperature variation and theoretical Lorenz number, thermal conductivity, thermal diffusivity, Thermal absorptivity, thermal resistivity and specific heat capacity were computed and compared accordingly. The results obtained show that stone coated steel has a good thermal comfort because it has the lowest thermal conductivity and lowest thermal absorptivity. Therefore it conduct less heat and absorb less heat, while zinc has high thermal conductivity and absorptivity, therefore the rate of heat conduction is very high and also absorb heat at a very high rate .
CONCLUSION
At the end of this research the results obtained has shown that material selection for roofing in building design has contribute immensely to the thermal comfort of occupant in building design.
In view of this, weather and climate of the particular location has to put into consideration. In a location where temperature is low zinc galvanized is the best roofing material because it conducts more heat and absorbs more heat than the aluminium coated and stone coated material.
In a location where temperature is high stone coated steel is the best roofing material in this location for good thermal comfort .For location with normal temperature, Aluminium coated is the best roofing material in that location.
RECOMMENDATION
Base on the results of comparative study of thermal properties some of roofing materials, the following recommendations are made for the builders in Nigeria:
- Builders in Nigeria should put climate and weather of particular location into consideration before choosing roofing materials to avoid thermal discomfort.
- Builders in Nigeria should go for the best roofing materials suitable for their location, without considering the cost implication for thermal comfort.
- Department of physics should provide adequate equipment for measuring thermal properties of solid material and make it accessible to students to make their research easier.
REFRENCES
- Al- Ajlan, S.A. (2006). Measurement of thermal properties of insulation materials by using transient plane source technique. Applied thermal engineering : 26 : 2191 Doi: 10.1016/jappthermamaleng, 20-04-2017
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- Ash,J., J. Baldwin, Hirt J., and Lance A.(2017) ―Heat conduction‖Virginia Technology University, retrieved from http// www.math .vt.edu/people/gao/class_home presentation /heat conduction. ppt
- Bauer W. and Westfall G.D., (2014). University physics with modern 2nd edition s physics published by McGraw –Hill USA.
- Bell J.M. & Smith G.B. (2017). Advanced Roof Coatings: Materials and Their Applications Retrieved from https//www.skycool.com.au/john 15 – 02-2017 04: 30
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- BS EN 12664:2001. Thermal performance of building materials and products Determination of thermal resistance by means of guarded hot plate and heat flow meter methods— Dry and moist products of medium and low thermal resistance. BSI; 2001.Pp76 ISBN: 0 580 36513 1
- Cahill, David G.(2017) “Measurement of thermal conductivity.” lecture. Univeristy of Illinois at Urbana-Champaign, http://users.mrl.uiuc.edu/cahill/thermal_school09.pdf.
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