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SELECTED ASPECTS OF SELF-HEATING BEHAVIOUR OF FAT CONTAINING FOOD POWDERS

The self-heating of milk powder deposit in drying devices has been identified as having the potential to cause a serious thermal hazard. The consequences of self-heating can result in disruption to equipment and installation, lost production time, degradation of product quality and that of the pr...

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Main Author: SHUIB, ANIS SUHAILA
Format: Thesis
Language:English
Published: Universiti Teknologi Petronas 2001
Subjects:
QD Chemistry
Online Access:http://utpedia.utp.edu.my/id/eprint/6815/1/2001%20Master-Selected%20Aspects%20Of%20Self-Heating%20Behavior%20Of%20Fat%20Containing%20Food%20Powders.pdf
http://utpedia.utp.edu.my/id/eprint/6815/
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spelling oai:utpedia.utp.edu.my:68152023-05-15T03:56:21Z http://utpedia.utp.edu.my/id/eprint/6815/ SELECTED ASPECTS OF SELF-HEATING BEHAVIOUR OF FAT CONTAINING FOOD POWDERS SHUIB, ANIS SUHAILA QD Chemistry The self-heating of milk powder deposit in drying devices has been identified as having the potential to cause a serious thermal hazard. The consequences of self-heating can result in disruption to equipment and installation, lost production time, degradation of product quality and that of the prime importance, ie. the danger to life. The preventive and protective measures have been designed and implemented in most dairy plants. In order to aid such efforts, the process conditions which could lead fires have been further investigated. The thermal kinetics of the dairy powders have been studied previously by some researchers but a number of related issues still require more in-depth study. A series of mathematical models simulating the self-heating behaviour of reactive materials have been developed and modified over time but experimental validation is not substantial. This project presents a study evaluating the thermal ignition kinetics of whole milk powder. It is an extension of a previous work in which a novel measurement procedure and a numerical simulation model were proposed (Chong, 1997). In this work, several new aspects has been addressed and experimental validations made. In particular, a much larger sample size was used, so that the effect of heat accumulated inside the sample was more pronounced to make the measurements more accurate. Previously, two reaction regime for whole milk powder were identified in the temperature range of 125°C to 160°C. However, the relationship drawn was not 100% convincing. The number of points plotted at low temperature range were perhaps insufficient to illustrate a definitive trend. In the current work, a similar test was conducted at ambient temperatures ranging from ll6°C (a much lower ambient temperature) to 150°C. The experimental data from this work were plotted together with the previous results which prove the reaction regime discovered by Chong(l997). Hence, the existence of at least two reaction mechanisms during self-heating of whole milk powder have been validated . The experimental conditions employed in this were then simulated using a numerical simulation programme. The experimental results recorded were compared with the simulation data. Some modifications were made to the program, based on the recent available information. The model was able to predict the self-heating behaviour of the milk powder in a larger sample size. From the sensitivity analysis, a more reliable thermal conductivity of milk powders was identified. Hence, the model produced more precise results compared with the experimental data. Further simulations were made on the effect of initial sample temperature and initial water content on the self-heating behaviour. In addition, the measurement techniques and activation energy of various composition of milk powder have been reported previously but the underlying reactions have still been less explained. Fat oxidation of milk powder has been claimed to be a major reaction triggering ignition. For this reason, a set of experiments was carried out to study the effect of fat content on self-ignition propensity. It was found that a large amount of fat can inhibit thermal runaway reaction. However, the presence of small fat component could also enhance the exothermicity. Therefore, a critical fat content in which self ignition may be more easily initiated has been suggested. Universiti Teknologi Petronas 2001-01 Thesis NonPeerReviewed application/pdf en http://utpedia.utp.edu.my/id/eprint/6815/1/2001%20Master-Selected%20Aspects%20Of%20Self-Heating%20Behavior%20Of%20Fat%20Containing%20Food%20Powders.pdf SHUIB, ANIS SUHAILA (2001) SELECTED ASPECTS OF SELF-HEATING BEHAVIOUR OF FAT CONTAINING FOOD POWDERS. Masters thesis, UNSPECIFIED.
institution Universiti Teknologi Petronas
building UTP Resource Centre
collection Institutional Repository
continent Asia
country Malaysia
content_provider Universiti Teknologi Petronas
content_source UTP Electronic and Digitized Intellectual Asset
url_provider http://utpedia.utp.edu.my/
language English
topic QD Chemistry
spellingShingle QD Chemistry
SHUIB, ANIS SUHAILA
SELECTED ASPECTS OF SELF-HEATING BEHAVIOUR OF FAT CONTAINING FOOD POWDERS
description The self-heating of milk powder deposit in drying devices has been identified as having the potential to cause a serious thermal hazard. The consequences of self-heating can result in disruption to equipment and installation, lost production time, degradation of product quality and that of the prime importance, ie. the danger to life. The preventive and protective measures have been designed and implemented in most dairy plants. In order to aid such efforts, the process conditions which could lead fires have been further investigated. The thermal kinetics of the dairy powders have been studied previously by some researchers but a number of related issues still require more in-depth study. A series of mathematical models simulating the self-heating behaviour of reactive materials have been developed and modified over time but experimental validation is not substantial. This project presents a study evaluating the thermal ignition kinetics of whole milk powder. It is an extension of a previous work in which a novel measurement procedure and a numerical simulation model were proposed (Chong, 1997). In this work, several new aspects has been addressed and experimental validations made. In particular, a much larger sample size was used, so that the effect of heat accumulated inside the sample was more pronounced to make the measurements more accurate. Previously, two reaction regime for whole milk powder were identified in the temperature range of 125°C to 160°C. However, the relationship drawn was not 100% convincing. The number of points plotted at low temperature range were perhaps insufficient to illustrate a definitive trend. In the current work, a similar test was conducted at ambient temperatures ranging from ll6°C (a much lower ambient temperature) to 150°C. The experimental data from this work were plotted together with the previous results which prove the reaction regime discovered by Chong(l997). Hence, the existence of at least two reaction mechanisms during self-heating of whole milk powder have been validated . The experimental conditions employed in this were then simulated using a numerical simulation programme. The experimental results recorded were compared with the simulation data. Some modifications were made to the program, based on the recent available information. The model was able to predict the self-heating behaviour of the milk powder in a larger sample size. From the sensitivity analysis, a more reliable thermal conductivity of milk powders was identified. Hence, the model produced more precise results compared with the experimental data. Further simulations were made on the effect of initial sample temperature and initial water content on the self-heating behaviour. In addition, the measurement techniques and activation energy of various composition of milk powder have been reported previously but the underlying reactions have still been less explained. Fat oxidation of milk powder has been claimed to be a major reaction triggering ignition. For this reason, a set of experiments was carried out to study the effect of fat content on self-ignition propensity. It was found that a large amount of fat can inhibit thermal runaway reaction. However, the presence of small fat component could also enhance the exothermicity. Therefore, a critical fat content in which self ignition may be more easily initiated has been suggested.
format Thesis
author SHUIB, ANIS SUHAILA
author_facet SHUIB, ANIS SUHAILA
author_sort SHUIB, ANIS SUHAILA
title SELECTED ASPECTS OF SELF-HEATING BEHAVIOUR OF FAT CONTAINING FOOD POWDERS
title_short SELECTED ASPECTS OF SELF-HEATING BEHAVIOUR OF FAT CONTAINING FOOD POWDERS
title_full SELECTED ASPECTS OF SELF-HEATING BEHAVIOUR OF FAT CONTAINING FOOD POWDERS
title_fullStr SELECTED ASPECTS OF SELF-HEATING BEHAVIOUR OF FAT CONTAINING FOOD POWDERS
title_full_unstemmed SELECTED ASPECTS OF SELF-HEATING BEHAVIOUR OF FAT CONTAINING FOOD POWDERS
title_sort selected aspects of self-heating behaviour of fat containing food powders
publisher Universiti Teknologi Petronas
publishDate 2001
url http://utpedia.utp.edu.my/id/eprint/6815/1/2001%20Master-Selected%20Aspects%20Of%20Self-Heating%20Behavior%20Of%20Fat%20Containing%20Food%20Powders.pdf
http://utpedia.utp.edu.my/id/eprint/6815/
_version_ 1768010119745896448
score 13.211869

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