Thermal Properties of Some Selected Materials Used as Ceiling in Building
AIM AND OBJECTIVE OF THE PROJECT
The aim of this project is, to measure the thermal properties of some material used as ceiling in building and to compare the values of each of them for thermal efficiency. These materials include PVC, POP, and ASBESTOS, CARDBOARD.
The objective of the project include,
- To measure their thermal absorptivity
- To measure their thermal diffusivities.
- To measure their thermal conductivity and determine their thermal resistivity.
- To calculate the density of each four sample.
REVIEW OF BASICS CONCEPTS
In this chapter a detailed review of thermo −physical properties of ceiling materials in building is considered. Also, a review of related literature is considered in detailed.
THERMAL CONDUCTIVITY (k-value)
According to Mohammed et al., (2010), the thermal conductivity 𝐾, is the property of materials that indicates its ability to conduct heat. Conduction will take place if there exists a temperature gradient in a solid (or stationary fluid) medium. Energy is transferred from more energetic to less energetic molecules when neighboring molecules collide. Conductive heat flow occurs in direction of the decreasing temperature because higher temperature is associated with higher molecular energy.
Thermal conductivity is regarded as the most important characteristics of a thermal insulation. The lower the thermal conductivity value, the lower the overall heat transfer. The thermal conductivity of insulating materials has been found to vary with density and temperature.
Measurement of Thermal Conductivity
Generally speaking, there are number of procedure in measure thermal conductivity, each of them being suitable for a limited range of materials, depending on the thermal properties and the medium temperature. The most commonly used methods are Lee- Charlton’s disc method and Lee’s disc method, for good and poor conductors of heat, respectively.
Lee’s Charlton’s Disc
Gesa et al., (2014) carried out experiment on measuring the thermal conductivity of insulator materials (P O P, Plywood, Isorel ) in Makurdi by using lee’s Charlton apparatus method. The results obtained from their experimental method, showed that, the lee’s Charlton apparatus method can be used in measuring the thermal conductivity of ceiling insulator materials.
Emmanuel et al., (2016) carried out experiment on measuring the thermal conductivity of insulator materials (P V C) in Calabar by using lee’s Charlton apparatus method. The result obtained from their method, showed that, the lee’s Charlton apparatus method can be used in measuring the thermal conductivity of ceiling insulator materials in building.
Alam et al., (2012) carried out experiment on measuring the thermal conductivity of insulator materials by using lee’s Charlton machine apparatus. The result obtained from their experimental method, showed that, the experiment method of lee’s Charlton machine apparatus can be used in measuring the thermal conductivity of insulator materials.
The diagram below is the lee’s Charlton disc apparatus with two thermometer, sample disc and two arrow showing steam in and steam out respectively (Gesa et al., 2014).\
MATERIALS AND METHODS
This chapter presents the materials and methods used in carrying out this research. A detailed description of the materials and their functions is presented as well as step by step description of methods for the research.
- List of Materials used: the materials used in measuring the thermal conductivity of the four samples ceiling materials are:
- Lee’s disc apparatus
- The experimental specimen in the form of a disc( ceiling sample)
- Three metal disc approximately 42mm x 12mm thick, each drilled radially to take a
- Two thermometers of 1500 C range
- Stop watch
- Weighing balance
- Micrometer screw gauge
- Vanier caliper
- An electrical heated disc of (6 to 12 volt) with wire lead out to 4mm sockets
- Special lamp stand
- A wooden frame for clamping the disc
RESULT AND DISCUSSION
In this chapter, the results obtained from experiments are presented and discussed in detailed. Since the investigation was done for different samples, the results are compared to find the best ceiling material for building insulation purposes.
SAMPLE MASS AND DIMENSIONS
The mass of each sample was measured with a weighing balance and their dimensions also measured with the aid of micrometer screw gauge and the vernier calipers. The results are presented in table
SUMMARY, CONCLUSION AND RECOMMENDATION
This chapter presents the summary and conclusion of this research. A detailed recommendation is given at the end of this chapter.
This research was focused on measuring the thermal property of some selected materials used as ceiling in building. Some of these thermal parameters include thermal conductivity, resistivity, diffusivity, absorptivity. Generally speaking, there are numbers of procedure in measure thermal conductivity, each of them being suitable for limited range of materials, depending on the thermal properties and the medium temperature. The most commonly used methods are Lee- Charlton’s disc method and Lee’s disc method, for good and poor conductors of heat respectively, but this research was limited only to the use of lee’s disc apparatus method.
Having use the instruments like lee’s disc machine apparatus, digital electronic weighing balance, micrometer screw gauge, Vanier caliper, stop watch and thermometers respectively, The results of thermal conductivity of all ceiling samples materials showed that, the POP ceiling has highest value of 0.1314 𝑤/𝑚𝑘 while the card board has the least value of 0.0851𝑤/𝑚𝑘, where the P V C (0.1083 𝑤/𝑚𝑘) and asbestos (0.1068 𝑤/𝑚𝑘) fall in between them. Also the results of thermal resistivity of all ceiling samples showed that, the thermal resistivity of card board ceiling has highest value of 11.7509 𝑚𝑘/𝑤 while POP has the least value of 7.6103 𝑚𝑘/𝑤, where the asbestos value (9.3633 𝑚𝑘/𝑤) and P V C value (9.2336 𝑚𝑘/𝑤)fall in between them.
Theoretically, a substance with a highest thermal conductivity value is a bad insulator while one with a least thermal conductivity value is a good insulator. In order words a good insulator materials will have high resistivity value for thickness other than 1m.
The results of thermal diffusivity of P V C were showed that, the P V C has the highest value of 6.34 (𝑚2/𝑠) x10−7 while asbestos has the least value of 0.60 (𝑚2/𝑠) x10−7, the pop with value of 1.20(𝑚2/𝑠) x10−7 and card board with value of 0.80 (𝑚2/𝑠) x10−7 fall in between them. Also results of thermal absorptivity of these ceiling materials showed that, the card board ceiling has the highest thermal absorptivity of 21.319𝑚−1 while P V C has the least thermal absorptivity of 7.573𝑚−1, where the POP (17.407𝑚−1 ) and asbestos (15.070𝑚−1) fall in between them.
In conclusion, thermal conductivity of four ceiling samples under this investigation were ranged from ((0.0851 − 0.1314 )w/𝑚𝑘 ).The results obtained corresponded to the results of previous researchers, which showed that, all the materials samples in this research are good insulating materials since their thermal conductivities fall within the range conductivities of construction and heat-insulating materials (0.023 − 2.9 𝑤/𝑚𝑘) according to Twidell and Mahhrer, (1982) and Weir, (1990) as cited in Emmanuel et al.,(2016).
If we come to classify ceiling materials base on the ceiling materials with good or best thermal
efficiency in building, then we can consider the thermal absorptivity for clarifications. Hence, the P V C and asbestos have the lower absorptivity value and the followed by POP, where the card board
has the highest value of thermal absorptivity. Therefore, the P V C and asbestos are the best ceiling insulating materials in building with best thermal efficiency and then followed with P O P, where the least ceiling materials best on thermal efficiency in building is card board.
Lastly, we can says that, the lower the thermal absorptivity value irrespective of lower or higher of thermal diffusivity portrays a good thermal insulation efficiency of ceiling materials in building.
- The builders should concentrate more on the insulator with good thermal efficiency when they come to the selection of ceiling materials in
- Best on the experience gained in this research, I suggest P V C ceiling as the best ceiling insulators materials in building.
- I recommended the Management of Federal University Dutsin-Ma to modernize the lecture classes that having ceiling which is not good in terms of thermal efficiency, and to stop using them purposely for the benefit of the student.
- People should switch from going to the most highly cost ceiling materials in building to the one with good thermal efficiency.
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