Construction and Application of Heat Sensor

ABSTRACT

Convenience and safeguarding our home appliances have become an important issue when dealing with an advancement and growth of an economy. This research focuses on the construction and application of a heat Sensor-monitoring system. The circuit works by monitoring temperature from an external input and comparing the temperature level with that of a preset temperature value. The power output of the circuit is cut off or switched OFF or an alarm is triggered ON if the temperature of the external input is equal to or, greater than the preset temperature value. The methodology involves the application of linear precision temperature sensors i.e., they generate a voltage that is directly proportional to the temperature. Basically the system is constructed using temperature sensors and comparators. The system is powered using a 12V power supply. The results of the tests showed that the power output of the circuit is switched OFF hence switching OFF the heating device or an alarm is triggered ON when the device exceeded a preset temperature level. The general operation of the system and performance is dependent on the temperature difference between the preset temperature value and external temperature intended to be monitored. The overall system was tested and found perfectly functional.

 

 

 

CHAPTER ONE

INTRODUCTION

 

 1.1 BACKGROUND OF STUDY

The word “heat” is made manifest as a result of increase in temperature. Temperature is most often measured environmental quantities which correspond to primary sensations-hotness and coldness. This is due to the fact that most biological, chemical, electronic, mechanical and physical systems are affected by temperature. In many instances, some processes perform better within a range of temperatures. Also, certain chemical reactions, biological processes and even electronic circuits do better within limited temperature ranges. When the needs to optimize these processes arose, the systems used for controlling the temperature within defined limits are then needed.

The temperature sensors are often used in providing inputs to those control systems. However, in the case of too much exposure of some electronic components to high extreme temperature, there will be an advance effect on them which can lead to the damage of the components. Though, some of the components can even be affected and get damaged by low temperature values.

Semiconductor devices as well as LCDs (Liquid Crystal Displays) can be affected and get damaged by temperature extreme. As the temperature threshold gets exceeded, an immediate action should be taken so as to prolong the lifetime of the system. In these, temperature sensing helps to improve the reliability as well as the lifetime of the system.

Most temperature monitoring devices are designed to respond to a particular (critical) temperature level. They are usually incorporated with different kinds of alarms and light indicator units, which are triggered ON at an unacceptable temperature level. These temperature monitoring devices work with temperature sensors normally transducers which generate accurate voltage output that varies linearly with temperature. They are mainly used for monitoring industrial machines, electric boilers, ovens and other heat energy related activities and this can be done by ensuring the temperature sensor and its leads are at the same temperature as the object to be measured. This usually involves making a good mechanical and thermal contact.

If the temperature sensor is to be used to measure temperature in liquid, the sensor can be mounted inside a sealed end metal tube and can then be dipped into a bath or screwed into a threaded hole in a tank. Temperature sensors provide inputs to those control systems. When temperature limits are exceeded, action must be taken to protect the system. In these systems, temperature sensing helps enhance reliability. In modern electronics, more temperature measuring techniques are available. Several temperature sensing techniques are in widespread usage.

The most common of these: Thermocouples, Thermistors and Sensor IC's. These temperature sensors ("transducers"), illustrate a nice variety of performance tradeoffs. Temperature range, accuracy, repeatability, conformity to a universal curve, size and price are all involved.

The temperature sensor being used in this system is the LM 335 and it has the following features; (1) Directly calibrated in Kelvin, (2) 1°C initial accuracy available, (3) operates from 400u.A to 5mA, (4) less than the 1H dynamic impedance, (5) easily calibrated and (6) low cost. This makes it preferable to the thermistor which was used in previous related research. Although, the thermistor has a wider temperature range than the LM 335, it suffers from self-heating effects, - usually at higher temperatures where their resistances are lower -and fragile, which makes it inappropriate for the research. Apart from the merits of the temperature sensor, the dual nature of the system extends its application which is not so in previous systems designed for heat monitoring.

The Complementary Metallic Oxide Semiconductor (CMOS), which provides reasonable performance, is extensively used in the construction of this system. In previous research relating to temperature monitoring, transistor-transistor logic (TTL) integrated circuits were used. The TTL devices are attributed to high power consumption, limited logic functions, narrow power supply, low compatibility and high overall cost while CMOS on the other hand, provides low power consumption, good immunity to external noise, insensitivity to power supply variations, temperature range capabilities -48°C to 52CC [1].

In general, the most important characteristics of CMOS make it the logic of choice. A typical temperature monitoring device possesses both a temperature sensor and control unit that responds to the input. It is against this background that the study wishes to examine the construction and application of heat sensor.

 

1.2 STATEMENT OF RESEARCH PROBLEM

The heat sensor is very important in the determination of temperature variation in our environment; it is mostly used in the hospital, heavy construction industries and petroleum industries. Despite the contribution, there are some limitation, which include; the inability to be use in all fields (health and manufacturing purposes). Another problem is the problem of cost of manufacturing and maintenance. Lastly there have been several studies on temperature but not even a single study have been carried on the construction and application of heat sensor; hence a gap in literature.

 

 1.3 AIMS AND OBJECTIVES OF STUDY

The main aim of the research work is to examine the construction and application of heat sensor. Other specific objectives of the study include:

1.     To examine heat transfers in microprocessors

2.     To determine the fundamentals of heat transfer

3.     To examine the components of heat transfer sensors

4.     To examine the temperature range in various heat sensors

5.     To determine the favourable environmental condition for heat sensors

1.4 RESEARCH QUESTIONS

The study came up with research question so as to be able to ascertain the above stated objectives of the study. The research questions for the study are stated below as follows:

1.     How does heat transfer in microprocessors?

2.     What are the fundamentals of heat transfer?

3.     What are the components of heat transfer sensors?

4.     What is the temperature range in various heat sensors?

5.     What is the favourable environmental condition for heat sensors?

1.5 ORGANISATION OF STUDY

The chapter one of the research work will contain the introduction, the study background, the statement of research problem, the aims and objectives of study, the research questions, and significance of study, the scope of the study and the definition of terms. The chapter two of the research work will contain the review of related literature as regard the construction and application of heat sensor. The chapter three of the research work will contain the materials and method required for the construction of the heat sensor. The chapter four of the research work will contain the experimental effect of the application of the heat sensor. The chapter five will contain the conclusion and the recommendation of the study.

1.6 SIGNIFICANCE OF STUDY

The study on the construction and application of heat sensor will be of immense benefit to the entire institution, the department, the students and other researchers that wishes to carry out similar research on the above stated topic as the findings of the research work is education people on fundamentals of heat sensors and also the experimental effect of the application of the heat sensor. The study finally will contribute to the body of the existing literature on the construction and application of heat sensor

1.7 SCOPE OF STUDY

The study on construction and application of heat sensor will cover the fundamentals of heat sensors and also the experimental effect of the application of the heat sensor.

1.8 DEFINITION OF TERMS

HEAT: Heat is the amount of energy flowing from one body of matter to another spontaneously due to their temperature difference, or by any means other than through work or the transfer of matter.

SENSOR: A sensor is a device that detects and responds to some type of input from the physical environment.

MICROPROCESSORS: an integrated circuit that contains all the functions of a central processing unit of a computer.