Design And Fabrication Of An Electric-Gas-Kerosine Powered Oven (Triplex Powered Oven)

ABSTRACT

Due to irregular power supply common in developing countries, as well as growing high cost of hydrocarbon, the need arises for the development of a triple energy source that uses electricity, gas and charcoal for heating oven chambers. The triplex-powered oven is a combination of components that make possible the use of alternative heat sources. The upper chamber is powered by electricity, the middle chamber is powered gas whilst the lower chamber works for the supply of gas located outside the chamber as a heat source and the third chamber is for gas. In the upper chamber is a heating element that generates and dissipates heat within the enclosure. The element is connected to a thermistor that regulates the rate of heat generation in the system. Cooking gas is supplied to the burner located in the lower chamber of the oven via a pipe connection to the gas cylinder while the heat required from the kerosine oven is supplied by the kerosine. Perforations allow for heat dissipation within the lower chamber. The performance test gave oven efficiency of 95.2 per cent. The oven can be adapted for both domestic and industrial purposes and have been found very useful in bakery industries

CHAPTER ONE

1.0                                                        INTRODUCTION

An oven is a thermally insulated chamber used for the heating, baking or drying of a substance and most commonly used for cooking.

This project is as a result of increasing interest. Essentially, the idea, as demonstrated in an existing design, arises in the project students a feeling of motivation, and hence the search for a way to bring it to reality in a simple, yet intelligent design, like this. This project is designed to make the students utilize as many theoretical and practical concept as have been instructed in Alston to mechanical engineering workshop technology. Students are expected to learn and apply concepts, principles about energy specially the conversions of  electrical energy to thermal energy, conduction and conventional heat transfer etc.

Also the determination of the properties of various ferrous and non-ferrous materials, electrical installation occults. The application of engineering measurement and quality control. Also to build an intellectual ability in interpretation of working drawing in designing and development before and after working process.  Students will get an opportunity to appreciate safety, and the use of both machine and hand tools in the course of working.

This oven is a combination of units and components that make possible the use of three alternative heat sources, namely electric and gas. The body is made of well coated mild steel while the internal surface is made of galvanized sheet owing to its resistance to rust or corrosion and does not contaminate the food substance in process. Fibre glass (rock wool) is stuffed in-between the mild steel and galvanized sheet and which acts to prevent loss of heat (insulation). Fibre glass is known to have light weight, high strength and high thermal shock resistance characteristics. The oven supports have rollers for easy movement and to absorb shock as well as sustain weight of the oven. At the upper chamber is a voltage indicator consisting of green and red bulbs. The former indicates the presence of electricity and the latter indicates when the oven is in operation. The oven has three door chambers. The upper chamber uses Electricity, the middle chamber uses charcoal while the lower chamber uses cooking gas as heat source, respectively. Inside the upper chamber is a heating element incorporated with a thermostat to regulate the rate of heat generation in the system. Wire mesh is welded to provide the required base or support for the baking trays. In the lower chamber of the oven is a gas burner connected by means of suitable hose to the gas cylinder located outside the oven.

Perforations created just below the burner allow for heat dissipation.

Electric ovens are the direct fired oven, which effectively distribute heat while being powered by electricity, although this can often result in a higher heating cost for the consumer. Many prefer this type of oven because they tend to use dry heat, which helps prevent the buildup of rust. Electric ovens also feature a temperature sensor (known as thermistor) that controls the oven’s temperature electronically, and many have top, bottom, or rear grill elements.

Electric ovens can take longer to heat, but they are relatively inexpensive in cost compared to other types of ovens.

In kerosene oven, It is of two categories: wick-burners and pressure-burners. Wick-burners utilize the capillary effects of fluids. The wicks draw-up kerosene from the reservoir and are eventually alight to produce flame as the source of heat. (See fig 1)

Pressure-burner is based on the principle of pressurized kerosene being preheated to vapor (atomization), which passes througha spreading device (orifice) and is ignited to heat up the utensils. The pressure is usually supplied through an air-pump

Gas oven one of the first recorded uses of a gas stove and oven referenced a dinner party in 1802 hosted by Zachaus Winzler, where all the food was prepared either on a gas stove or in its oven compartment. In 1834, British inventor James Sharp began to commercially produce gas ovens after installing one in his own house. In 1851, the Bower’s Registered Gas Stove was displayed at the Great Exhibition. This stove would set the standard and basis for the modern gas oven. Notable improvements to the gas stove since include the addition of the thermostat which assisted in temperature regulation; also an enamel coating was added to the production of gas stoves and ovens in order to help with easier cleaning.

Gas oven is one which works by the liquefied petroleum gas for the baking of the bread, cake and biscuit.

The major operational principle of the gas oven is the process of heat transfer. Heat transfer tends to occur whenever there is a temperature difference, and the ways in which heat may be transferred in the gas oven that is convection. Convection is the transfer of energy from one place to another by the motion of a mass of materials between the two points. In a natural convection, the motion of the fluid is entirely as a result of differences in density resulting from temperature differences. Naturally, convection occurs when a solid surface is in contact with a fluid of different temperature from a surface. Density differences provide the force required to move the fluid (moisture) in the food. In the oven, the fluid involved is the enclosed air and the burner surface, which provides the solid surface, while the oven walls serve as the solid surfaces. The rate at which heat is transferred across an enclosed oven is calculated from a coefficient based upon the temperature differences of the surfaces.

1.2                                            OBJECTIVES OF THE PROJECT

This project is undertaken to:

(1)    Compare the various ways used in the production of an electric, kerosine and gas oven.

(2)    Disclose the different types of process in the manufacturing of an electric oven, kerosine and also a gas oven in the past in comparison to the modern days method.

(3)    Exploit the local facilities available in the construction of the oven as against imported ovens.

(4)    To exhibit the usefulness of a multi- power source purpose oven in the economy and technology growth of the nation.

(5)    To know the convenience in the use of alternate power source for operation of ovens.

(6)    Discover the basic principle involved in the design and maintenance of a triplex purpose oven.

1.3                                                IMPORTANCE OF OVENS

In actual analytical enunciation an oven is an enclosed chamber in which things are heated or cooked with various sources of power. Its importance borders around its function, which are as follows;

(i)    It is used to meet the everyday basic need of cooking, (baking, toasting, gritting, toasting) of food materials for human consumption.

(ii)    Ovens are used for heat treatment of substance in laboratories and industries.

(iii)    Also as a means of preservation by heat application to perishable materials (organic and inorganic) in general.

(iv)    Sterilization of instruments and equipment for industrial use is done by heat application using oven.

(v)    Expelling of moisture content to a required measure in some substance is also done using oven.

(vi)    Early manufactured ovens where used as a source of room heaters during cold weathers in cold climates.

Other importance boarding around its energy source is that the use an alternative source of energy when either fossil fuel or electricity is not available.  This can be relatively save cost when necessitated.

1.4                                                 LIMITATIONS OF OVEN

Disadvantages in the use of ovens:

(i)    Cleaning and repair is a difficult and time- consuming endeavor.

(ii)    Expect for mass production singular construction is relatively expensive to produce.

(iii)    If precautions are not well carried out, it can result in fire hazard, which is dangerous to life and properties.

(iv)    Because ovens provide heat for one or more areas, the temperature may vary in different areas of the oven.

(v)    Oils and moisture collected on metal surface can end up trying to rust the metal coating if not clean regularly.

(vi)    It is expensive to operate in high volume operations.

(vii)    Speed seem to be the key factor and time taken to get to required constant temperature can be wastage of time.

(viii)    Access to internal component n case of adjustment and maintenance is tasking as it requires an entire disassembling.

(ix)    In case of mechanical faults resulting from shut down, an entire disassembling and requires is required.

(x)    Due to its function by heating, there is always a premature wear or mechanical failure of some of the internal component.

1.5                               PURPOSE OR OBJECTIVE OF THIS PROJECT

This study is to devise a means of producing an oven with three different power source (that is, electric, gas and kerozine) to address the following:

(1)            The problem of sooty pare-heating as observed in vaporizing cookers.

(2)             Economically, this equipment is designed for cost reduction and easy to maintain.

(2)        To meet up with inadequate availability of fire wood through deforestation.

1.6                                       SIGNIFICANCE OF PROJECT

This project work is intended to serve as a catalogue and manual for the construction, installation, maintenance and repair of different possible faults in electric oven, it is also of a great benefit to the department and society as it will serve as medium of knowing the principle of operating the model work. It serve as a standard means for cooking.

1.7                                         DELIMITATION OF THE PROJECT

1. There is freedom of location and general adaptability.
2. It entails good cooking condition, cleanliness, quietness and ambient temperature.
3. Uniform of temperature within narrow limit with the electrical chamber.
4. Capital cost, running and maintenance cost of oven are low.

1.8                                              DEFINITION OF TERMS

THERMISTOR: Thermistors are thermally sensitive resistors whose prime function is to exhibit a large, predictable and precise change in electrical resistance when subjected to a corresponding change in body temperature. Negative Temperature Coefficient (NTC) thermistors exhibit a decrease in electrical resistance when subjected to an increase in body temperature and Positive Temperature Coefficient (PTC) thermistors exhibit an increase in electrical resistance when subjected to an increase in body temperature

HEATING ELEMENT: This is a conductor material that is designed to heat up when connected to current flow. It converts electric energy into heat energy.

OUTLET PLUG: This is an electrical device design with two or three metal pins that fit into holes in a socket to make an electrical connection.

SWITCH: This is a device used to connect or break the flow of electric current in a circuit.

INDICATOR (LAMP): This is a device which glows like a bulb indicating the working status of a connection.

CABLE: A cable is a material or conductor use in conveying electric current from one point to another.

CHAPTER TWO

2.0                                                    LITERATURE REVIEW

2.1                               HISTORICAL BACKGROUND OF OVENS

The first historical record of an oven being built is in 1790, in Alsace, France as written by Mary Bellis in her work : Brief history of cost iron stoves in America.

This oven was made entirely of bruks and tile.  At about 1728, cast iron ovens were made in large quantity.  The first stove of German design are called five plate or jamb ovens.  A progression of invented oven differed due to the fuel used.