Group members:
Jawwad Hassan
Hamza Tariq
Saad Ali
Course:
Control Sytems - I
Instructor:
Sir Abdul Afram
INTRODUCTION:
The proposed system would use heated water to control the temperature of the room. Heated water would be circulated in a room by motorized pump. The motor would be controlled by a microcontroller. A thermistor would provide the temperature input to the microcontroller. The microcontroller will process the raw input, and then turn the motor on/off by comparing the current temperature with the required temperature set by the user.
The complete project requires the use of AC motor pumps and instant geysers. However, for demonstration purposes, working of a small working prototype has been described below.
APPLICATION:
· The proposed has been designed to control the temperature of a medium sized room. This is achieved by using a conventional water pump to circulate the water through pipes. The water is passed through an instant geyser which heats it up.
Instant geysers fire-up when water is passed through them, otherwise they are dormant. This system controls the circulation of water by controlling the motor, which in turn controls the geyser. Therefore, efficiency and economy of both gas and electricity is achieved through this method of heating.
· Another application by some modification is the incubator. Incubator requires a constant temperature to be maintained. And this system provides an efficient mechanism for controlling the temperature in an incubator.
Different types of water control
led heating systems are used world wide.
In general, heating apparatuses implement apparatuses that supply warm water to a heating system, etc., which burn fuel therein, such as gas, heat heating water using combustion heat created by the combustion, and then heat the inside of a room by circulating the heating water through heat pipes provided in the floor, etc. in the room, or supply hot water using the heating water.
Control methods for maintaining the interior temperature at user-desired setting temperature in this heating apparatuses can be divided into
a) A method of turning on/off a heating apparatus by measuring the interior temperature.
b) A method of turning on/off a heating apparatus by measuring the temperature of water in a heat pipe.
c) A method of continuing operation for a time set by a user and stopping the operation for a time set in advance.
Such kind of a system is provided by “WARMA FLOOR” company situated at Hampshire,UK. That is an underfloor heating and cooling sys
tem. In this system heating and cooling pipes are installed in the floor of each room. Water is given a constant temperature by any kind of heating mechanism(gas,oil or biomass). Individual temperature control is provided for each room. Each room has a thermostat installed. This individual room temperature control system comprises of internal and external sensors connected to a controller and mixing valve with water flow temperature sensor which mixes the heated water with colder water according to requirement.
BLOCK DIAGRAM: EXPLANATION OF DIAGR AM COMPONENTS:
The different blocks of the block diagram function in the following manner:
Input temperature
The user is provided three preset modes for selecting the required temperature. The temperature can be selected using a switch. The three temperature modes are listed as:
i. Warm
ii. Hot
iii. Very hot
The selected temperature mode is directly fed to the microcontroller.
Processing block
The processing block consists of an Analog to Digital converter (ADC) and a microcontroller. The ADC converts the analog voltage input from the thermistor to digital output. The output of the ADC is then fed into the microcontroller for processing. Microcontroller compares the temperature value received from the thermistor to the temperature mode selected by the user. If the current temperature is less than the required temperature as per the selected mode, microcontroller gives a command to the motor control to start the motors and vice versa.
Motor control and display
The motor control receives input from the microcontroller. The main component of this block is the H-Bridge and the motor that pumps the heated water through pipes for the room heating. The motor is started or stopped as per the input from the microcontroller.
Display is provided by a group of 7-segment displays. The display provides information about the current ambient temperature and the selected mode of operation.
Thermistor
Thermistor is a temperature sensitive device that varies its output voltage according to the temperature. This block will provide current ambient temperature value to the processing block.
SCHEMATIC:
DESCRIPTION OF CIRCUIT COMPONENTS:
LM35 Thermistor
The LM35 series are precision integrated-ci
rcuit temperature sensors, whose output voltage is linearly proportional to the Celsius (Centigrade) temperature. The LM35 thus has an advantage over linear temperature sensors calibrated in °
Kelvin, as the user is not required to subtract a large constant voltage from its output to obtain convenient Centigrade scaling. The LM35 does not require any external calibration or trimming to provide typical accuracies of ±1⁄4°C at room temperature a
nd ±3⁄4°C over a full −55 to +150°C temperature range.
For our project, LM35 provides the tem
perature input to the microcontroller through the ADC.
ADC0804 Analog to Digital Converter
The ADC0804 is a CMOS 8-bit successive approximation A/D converter that uses a differential potentiometer ladder. The A/D appear like me mory to the microcontroller and no interfacing is required.
For our project, ADC0804 converts the analog output of the thermistor to digital values, so that is can be processed by the microcontroller.
89c51 Microcontroller
The AT89C51 is a low-power, high-performance CMOS 8-bit microcomputer with 4K bytes of Flash programmable and erasable read only memory (PEROM). The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory programmer.
In our project, the 89c51 microcontroller is the main brains of the system. It processes the digital temperature input from the ADC and compares it to the mode set by the user. After comparison, decides upon running the motor for water circulation.
7-segment LED displays
A seven-segment display is a form of electronic display device for displaying decimal numerals that is an alternative to the more complex dot-matrix
displays. Seven-segment displays are widely used in digital clocks, electronic meters, and other electronic devices for displaying numerical information.
For our project the 7-seg displays will show the current ambient room temperature and also the mode of operation selected by the user.
TIP Power transistor
The power transistor is used to control the motor. Control signals from the microcontroller are used to turnthe motor on and off.
DC Motor
The motor used here is a 12V DC motor. The motor is controlled by the H-Bridge outputs.
In our project, motor is used to pump the heated
water through pipes for controlling the room-temperature.
MECHANICAL STRUCTURE:
The only mechanical component present in the system is a DC Motor that will pump the heated water. The water will be stored in a small reservoir on top of the motor. The most feasible choice would be to use a PET bottle. Water will flow into the motor through the reservoir, and then it will be pushed into the pipes for circulation. After completing a full cycle, water will again fall into the reservoir. Along the way, the water would be heated by some electrical or gas heater.
SOFTWARE PSEUDOCODE:
· The digital thermistor input is received by the microcontroller through the ADC.
· This 8-bit binary input is converted to decimal using the bin-dec conversion formula.
· The raw adc value is then converted to temperature reading using the following formula:
Temperature at any x = (value received-value at 0) / (value at 100 - value at 0)x100
· The received temperature value is then compared with the temperature mode set by the user.
· If the received temperature is less than the required temperature, output is given to the motor to start working, else the motor is stopped.
· The temperature input is decoded into a 7-segment output, and the result is displayed on two 7-segment displays.
· The mode of operation is also converted to 7-segment output, and the result is displayed on the 7-segment display.
· In the end, a delay of 1 sec is generated to make the LED readings more readable.
SOFTWARE FLOWCHART:
http://rapidshare.com/files/397135000/PCB_design_files.zip
The proposed system provides an effective, efficient and economical solution to the problem of heating a conventional sized room. Also, through a little modification, the system can be used for some other temperature control purposes like controlling the temperature in an incubator.
Can you please reupload the pcb file and hex file
ReplyDeletePLEASE SIR UR LINK OF FILES TO DOWNLOAD IS NOT WORKING PLEASE HELP WITH THIS
ReplyDeletehi can you send the code to rajus023@gmail.com
ReplyDeletethe link which you have given is not working
ReplyDelete