Microcontroller Based Oven Temperature Control With Digital Display

ABSTRACT

The design and construction of microcontroller based electric oven and cooker with time and temperature control is presented in this project. The project is built around an Atmel 89C52 micro controller which is programmed to carry out some user defined function. The project is design to meet the safety requirement that is lacking in many similar systems in the market and also make it operation as easy to operate as possible. The microcontroller unit was interfaced with some other components to achieve the set objectives. A temperature sensor senses the temperature of the oven units which is in analogue form and fed the output voltage to the input of the analogue to digital converter (ADC) which convert the analogue signal to a digital equivalent signal. The microcontroller performs the mathematics and display the result appropriately on the display unit.

CHAPTER ONE

1.1                                                        INTRODUCTION

Oven Temperature Controller is used in most of the manufacturing industries. The industries like textile mill, pharmaceutical industry, oil refinery etc. all requires temperature controller. The temperature controllers are used to maintain constant temperature of process or plant or any material. In such temperature controller system there is one reference temperature called set point or set temperature that is the desired temperature that must be maintained. This reference temperature is set by external means. Also it can be always adjustable according to requirements. Once this temperature is set the system tries to maintain it by sensing the current temperature and controlling it using heater, cooler or compressor.

It senses current temperature, compares it with reference temperature and generates error signal. Then based on this error signal it controls heating element (or cooling element). If set temperature is more then error signal is negative and vice versa.

Temperature control system that senses current temperature using temperature sensor. It compares it with the set temperature that is set by external reference. And it gives indication of error signal as positive or negative.

• If error is positive that means current temperature is more than set temperature that has to be reduced
• If error is negative that means current temperature is less than set temperature and it is required to increase it

1.2                                        AIM/OBJECTIVE OF THE PROJECT

The objective of the is to design a device that can be used to measure the Temperature display them on a LCD. Temperature is sensed by respective sensor and sensor output is amplified and given to ADC. Microcontroller controls this parameter and keeps it at some predefined levels using relay interface.

1.3                                         SIGNIFICANCE OF THE PROJECT

Oven Temperature controller is needed in any situation requiring a given temperature be kept stable. This can be in a situation where an object is required to be heated, cooled or both and to remain at the target temperature (setpoint), regardless of the changing environment around it.

• This oven offer more even and uniform baking and browning. Because of the fan, the heating is more equally spread throughout the chamber, and this means more consistent baking of food.  The edge of that cake is just as well cooked as the middle.
• You can often achieve the same degree of cooking in a food with lower oven temperature settings, due to added heat transfers to the food via the fan driven convection air currents.
• Also, you can bake more than one item at a time without affecting the oven’s baking ability.  The internal operation of convection units relies less on the radiant heating patterns, and more on the even flow of hot air.  So, blocking those heat rays from the elements or burners with a second pan or tray of food to bake at the same time, has less negative effect on the oven’s performance than it might in a conventional oven.
• Therefore, with a properly sized fan, convection ovens have fewer hot and cold spots within, due to their more uniform heating characteristics. Thus, the entire interior assumes roughly the same temperature.
• With fewer hot and cold spots, the internal oven temperature is easier to precisely control, and particular temperature settings yield more consistent and repeatable results.
• Food placement within the convection oven is less critical as well.  The forced air circulation within helps assure that whether you place a cake on the top, middle, or bottom shelf, that it will bake to the same degree, given the same temperature and amount of baking time.
• This oven with the fan inside are less impacted by lining their shelves with aluminum foil for example, to contain messes, again, because you need not worry about blocking some of the radiant heating. We did this once in our traditional oven, and wondered why it took so long to bake our pizza. But sitting items on cookie trays or aluminum foil in a convection oven should cause no bake time increases.
• They generally brown foods faster than non forced-air oven types.
• These ovens run cooler. The heating elements need not be heated to such high temperatures because more of the heat they produce actually reaches the food being cooked. Plus, the circulating air reduces the number and degree of “hot spots” both within and outside the oven.
• Cooler overall operating, means longer life for the oven’s internal components, although the fan itself could fail frequently, since it features moving parts (the motor and blade), as noted below.
• This ovens can use less energy and time to cook the same amount and type of food to the same degree.

1.4                                           LIMITATION OF THE PROJECT

• Opening the door during baking can drastically increase food cook times, by interfering with the convection currents inside. So keep the door closed until it’s time to remove the food.  If you like inspecting your cakes while they’re baking, buy a convection unit with a window in its door.
• A limit controller is often used in conjunction with a loop controller. It will generally accept a variety of inputs such as thermocouple, RTD, or process inputs, then allowing for high or low temperature inputs to be set. Oven controllers are used in a variety of applications, particularly industrial ovens and furnaces applications as well as by the life science industry.
• Though you can cook more items at the same time, be careful of how you place the pans. To avoid choking off air flow, leave an inch or so of open space between each tray, dish, or other baking container. Air flow is probably the single most important ingredient in a well-operating convection oven.
• Fan assisted convection ovens can be noisy, depending on the size and quality of the fan.
• A cook used to baking in a conventional oven will certainly need to experiment with a oven to master its peculiarities.  Some foods can cook to the same degree, in half of the time that it would take them to do so in a traditional radiant oven.

·        ovens generally cost substantially, However, they may pay for themselves over time in reduced energy costs and better tasting food.

1.5                                      APPLICATIONS AND ADVANTAGES

1. This project can be used in Mechanical companies to measure various parameters of operating machines like temperature.
2. Can be used in green houses to control the temperature
3. Temperature monitoring and controlling action can be used in home or various halls like conference room, seminar hall to control the temperature of room.
4. Ovens are used to sterilize items that might be damaged by moist heat or that are impenetrable to moist heat.