REPORT ON TEMPERATURE CONTROLLED FAN REGULATOR

(Innovation Product)

By,

SANI DAHIRU BUBA

GS 34084

Course Code: EAS5101Course Title: INNOVATION STUDIES 1Lecturer: Dr. AZMIN SHAKRINE MOHD RAFIE

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1.0 Introduction

Ventilation generally falls within the domain of another branch of Engineering commonly

referred to as HVAC. A heating system (“H” in HVAC) is designed to add thermal energy to a

space or building in order to maintain some selected air temperature that would otherwise not be

achieved due to heat flows (heat loss) to the exterior environment. The heating system is

accomplished using central heating system or portable electric heaters or traditionally by burning

coal in a fireplace which is mostly applicable to temperate climates. A ventilating system (“V”)

is intended to introduce air to or remove air from a space, that is, to move air without changing

its temperature. Ventilating systems may be used to improve indoor air quality or to improve

thermal comfort. Ventilating systems are accomplished using fans of various sizes and

arrangements depending on the need or traditionally using hand fan. A cooling system ("C"

which is not explicitly included in the HVAC acronym) is designed to remove thermal energy

from a space or building to maintain some selected air temperature that would otherwise not be

achieved due to heat flows (heat gain) from interior heat sources and the exterior environment.

Cooling systems are normally considered as part of the “AC” in HVAC; AC stands for air-

conditioning [1]. HVAC is one of the largest consumers of energy in residential,

public, commercial and the hospitality industry, constituting approximately

30 percent or more of total costs. HVAC systems that operate properly are

essential in lodging facilities and contribute to employee productivity and

guest satisfaction.

A ventilation system was defined in [2] is a system which circulates fresh air throughout

a confined space or spaces, while removing contaminated or stale air. Ventilation systems are

used in various settings, including homes and workplaces. Some of the application of these

systems may include maintaining a constant humidity and temperature, getting rid of dust and

allergens from the air and providing the proper exchange of oxygen and carbon dioxide levels.

There are various types of ventilation systems, which are typically classified as natural or

mechanical systems. A natural ventilation system relies on atmospheric conditions, while a

mechanical system is a man-made device that assists in the filtration and circulation of the air.

The most common form of a natural system consists of an outlet on the roof and openings

throughout the lower part of a building. This allows air to rise and exit through the roof, and new

air to enter from below, providing constant circulation. Mechanical ventilation systems actively

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pull fresh air in and push stale air out. They may have other capabilities, including heating and

cooling, and require some form of energy to operate. One common form of mechanical

ventilation system is the heating, ventilating, and air conditioning (HVAC) units which are used

in homes and other buildings.

Advanced ventilation systems are used within certain industries as a safety measure. This

kind of mechanical ventilation system may be required by law, depending on the industry. They

are often required in mining, underwater, and majority of manufacturing industries. The exact

type of advanced mechanical ventilation system used will ultimately depend on the individual

needs of the company and any applicable laws. Some of these industries may have to comply

with stipulated air quality guidelines regarding requirements of such equipment. This may be

dependent upon the geographical location of the particular facility. The main purpose of

ventilation systems in such settings is to filter harmful substances from the air, provide a constant

supply of oxygen, and maintain a healthy atmosphere for breathing. A ventilation system can be

used in conjunction with other equipment to establish desirable temperatures and to maximize

the air circulation. It is not uncommon for large buildings and warehouses, kitchens and

washrooms to be equipped with exhaust fans that assist in bringing in fresh air in while pushing

the stale air out. These fans may be placed at various ventilation openings throughout the

building or on the roof. A ventilation system with exhaust fans are often used in buildings that

generate substantial amounts of heat or contain fumes [3].

Some exhaust fans operate continuously and many operate when not necessary. When

building codes and standards permit, it is important to turn exhaust fans off when they are not

serving a useful purpose. There may be opportunities to more efficiently control exhaust fans in

areas such as restrooms, locker rooms, showers, gymnasiums, laboratories, custodial closets,

dedicated copy rooms, laundry rooms, food preparation spaces, and other locations. Better

control of exhaust fans not only saves the electricity required to operate the fan but also the cost

of conditioned air that is exhausted unnecessarily. In the case of restrooms, exhaust fans can be

rewired so that fans operate only when restroom lights are switched “on.” Even if fans are best

left on when a building is occupied, at least savings are realized during unoccupied hours.

Another option is to install occupancy sensors to control both the exhaust fan and lighting

circuits. A wide variety of manual, electronic and programmable timers are also available for use

where fan operations are related to the scheduled use of a space. In facilities where building

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automation systems (BAS) are utilized, exhaust fans can be controlled directly through the BAS

and set for scheduled occupancy use. In the case of gymnasiums, it is often preferable to control

exhaust fans with a thermostat when exhausted and makeup air are used primarily to maintain

the most comfortable conditions possible during the summer months. Behavior awareness is

always a good starting place to encourage building occupants to keep exhaust fan and lighting

circuits off when not in use [4].

1.2 Problem statement

Occupants of residential and commercial premises where fans are installed

experience a lot of fatigue and inconvenience while changing the speed of

fan manually as the room temperature changes. It is even a more difficult

task for children and the elderly. Also, considering Malaysia as a tropical

country, temperature changes are very drastic especially during the

monsoon rains. Fan speed set at high speed in the morning hours due to

heat will waste a lot of energy in the afternoon after rainfall when the

temperature becomes low and the fan is still set at high speed. Therefore, a

strong justification is made by designing a temperature controlled fan

regulator whose speed is automatically regulated according to the ambient

temperature.

1.3 Objectives

The main objective of this work is to design and implement a “Temperature

controlled fan regulator” to satisfy the problem statement. This will be

achieved by addressing these specific objectives;

1. Obtain a suitable circuit diagram and adapt to local requirements.

2. Produce a printed circuit board and implement the design.

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Figure 1 Typical fans used in homes and workplaces and accessories

1.4 Significance

The temperature controlled fan regulator is significant because;

1. It would be cheaper than the conventional fan regulator when mass

produced.

2. It would save electrical energy by automatically adjusting current flow

when the ambient temperature reduces so that the fan rotates slowly

and thus consume less energy.

3. It will be more durable than the conventional fan regulator as there are

no moving parts.

4. It will be easy to operate, once switched ‘ON’, it is self-regulating

depending on the prevailing ambient temperature.

5. It provides a cheap and robust method of fan speed control when

compared to the other products reported in the literature review.

2.0 Literature Review

]

Zulkifli [5] reported the design of an automatic room temperature control incorporating a

security system using PIC16F876A microcontroller which drives a power transistor (BD135) and

hence drive a brushless DC fan, LEDs and buzzer when the temperature varies above or below

certain temperatures ranges. The value of the temperature is displayed on an LCD screen. The

circuit uses two temperature sensors placed at different locations for the purpose of monitoring

the temperature. The system operates in three different conditions depending on

the range of temperature. If the current value of temperature is higher than

desired value, the fan will start functioning and LED will indicator high

temperature. On The other hand, if the temperature increases and reaches a

desired value, the fan will stop functioning and LED will indicate normal stat.

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Finally, if the current temperature is lower than the desired value, fan will

not function and LED will indicate low temperature. Any changes in

temperature in the room is continuously monitored and displayed on the

LCD. In addition the LEDs are used to indicate the current state and range of

temperature in the server room. The project is basically aimed at monitoring

the room temperature and tries to minimize it when it reaches a certain

preset value. It differs slightly from the project under consideration although

the applications are similar. Furthermore, the project is very expensive

because of the cost of microcontroller and also requires and external DC

power supply.

Alvasim et al. [6] reported the design of a remote controlled fan regulator where the

speed of a fan is controlled by using a remote switch similar to the DVD remote

switch. The variation in the firing angle of Triac is used for regulating the fan

speed. Any button on the remote can be used for controlling the speed of the

fan. Using the remote switch, the speed of the fan can be regulated while

sitting on the couch or bed and has five variable speeds. This project shares

a certain similarity with the current study in that both regulate the speed of

a fan. However, it is more expensive than the product considered in this

study because of the use of infra-red sender and receiver.

Nazar [7] reported the design and construction of an automatic control room temperature

using PIC with LCD display. The product operates automatically based on the changes of room

temperature. For the detection of room temperature, a temperature sensor (LM35DZ) is used to

send signal to microcontroller (PIC16F876A) which decides to increase or decrease the speed of

the fan based on the received signal from temperature sensor. This product is also expensive

because of the PIC controller and will require a separate power supply but it is also a self-

regulating system once switched on. Abd. Ghani [8] also reported the design of a

microcontroller based smart fan system. The electric fan automatically

switches the speed according to the environmental temperature changes.

The system consists of a combination of sensor, controller, driver and motor

with integration of embedded controlled programming by means of

MC68HC11A1 as the main controller.

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Norazmi [9] reported the design of temperature control system for a

server room. The system consists of temperature sensor, PIC, LCD, driver

circuits, AC air heater and AC motor. Three drivers are used for triggering

process to switch on the AC heater and another two are for triggering levels

of the motor. The motor operates on the basis of two temperature ranges,

meaning it has two levels of speed. The function of this system is for

controlling the internal temperature of a regular room automatically. It will

operate based on the values or ranges of temperature in the room which is

detected by the temperature sensor. If the temperature in the first range

(0ºC to15ºC), the air heater will operate to heat the server room which in

very cold temperature. If it is in the second range (16ºC to 25ºC) the system

will not be enabled because it’s achieving normal temperature range. If

temperature is in the range26ºC to 40ºC, the motor will be triggered for level

1 to decrease the temperature value. If it is more than 40ºC, the motor will

be triggered for level 2 and its speed becomes faster at this level. Both

output devices are considered important to maintain a constant temperature

in the room. This system can be categorized as an automatic system.

In summary, from the previous work reviewed, it was found that most

of the works except one centered on control of room temperature, whereas

this study is concerned with the regulating the speed of fan based on

temperature. The applications are quiet similar, but they have a

disadvantage of cost and also the products need an external power supply to

operate unlike the proposed temperature controlled fan regulator which uses

AC supply and also is much cheaper.

3.0 Methodology

The temperature controlled fan regulator (TCFR) would be implemented in

the following simple steps;

1. The basic circuit was sourced from the internet.

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2. The circuit was adapted for 240V, 50Hz supply system suitable for use

in Malaysia.

3. The modified circuit diagram was redrawn using ISIS Professional

Software.

4. The printed circuit board (PCB) was produced and the circuit was

constructed.

5. The product was tested and packaged.

3.1 Circuit description

The main component in the circuit diagram of Figure 1 is the Triac. It is an electronic component

approximately equivalent to two silicon-controlled rectifiers (SCRs/Thyristor) connected in

inverse parallel (paralleled but with the polarity reversed) and with their gates connected

together. The formal name for a Triac is bidirectional triode Thyristor resulting in a bidirectional

electronic switch which can conduct current in either direction when it is triggered (turned on)

and thus doesn't have any polarity. It is triggered by applying either a positive or a negative

voltage to its gate electrode (with respect to A1, otherwise known as MT1). Once triggered, the

device continues to conduct until the current through it drops below a certain threshold value

known as the holding current, such as at the end of a half-cycle of alternating current (AC) mains

power. In addition, applying a trigger pulse at a controllable point in an AC cycle allows the

control of the percentage of current that flows through the Triac to the load (phase control). The

Triac used in this circuit is BT136. It is Thyristor with a firing angle nearly 45 0. A snubber

circuit consisting of a resistor and capacitor is used to control the firing angle of Triac. This

firing angle determines the speed of the fan.

3.2 Principle of operation

This fan regulator circuit will automatically control the speed of the fan according to the

temperature. Two thermistors (R1 and R2) are used as the temperature sensors. When the

temperature is increasing, the resistance of R1 which is a thermistor with negative temperature

coefficient (NTC) decreases and at the same time the resistance of R2, a thermistor with positive

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temperature coefficient (PTC) increases. The rate of change of the resistance will be different for

R1 and R2. When the resistance is varied the firing angle of the Triac changes and so do the

speed of the fan.

Figure 2, Basic circuit diagram of a temperature controlled fan regulator

3.3 Design Analysis

In Malaysia, the single phase supply is rated at 240V, 50Hz. According to a study conducted in

[10], a ceiling fan operated on slow, medium and high speeds consumed 53, 66 and 73 watts

respectively. Therefore, an average of the three fans power consumption of 64 watts has been

considered as the power rating of the fan in this design. Since the voltage and power are known,

the current taken by the fan can be calculated from Ohm’s law in equation 1.

I= PV (1)

I=64240

=0 .27 A

According to IEE wiring regulations, a lighting sub-circuit should be protected by a 5A fuse,

therefore a fan fitting is considered as a lighting point in this case, hence the use of 5A fuse in

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series with the switch in Figure 3. The inductor L1 is in series with the fan, therefore a current of

0.27A would pass through the inductor which can handle it safely.

Capacitors are voltage controlled elements, they were selected based on the circuit

voltage of 240V and hence each is capable of handling this voltage safely. The Triac and Diac

were selected based on their current capacity which is about 4A, this value is much higher than

the current flowing through the circuit, i.e. 0.27A.

The voltage appearing across R1, R2 and R3 can be found from potential divider

principle as in equation 2.

V R 1=V s×R1

R1+RT (2)

Where RT =

R2×R3

R2+R3 (3)

From equation 3, RT=5 k×6 . 8 k

5 k+6 . 8 k=2 . 9 k

Therefore V R 1=240×100 k

100 k+2 .9 k=233 V

V R 2=240× 5 k5 k+2 .9 k

=152V

Because R2 and R3 in parallel, the voltage drop across them is slightly less than that across R1

which is usual.

3.4 Summary of Components

I. The circuit can be assembled on a Vero board.

II. L1 is a70uH inductor.

III. C1 and C2 are polarized Capacitors and must be rated at least 250V.

IV. C3 is also a polarized Capacitor must be rated at least 600V.

V. BT136 is a Triac which must be able to handle about 4A load current.

VI. F1 should be a 5A fuse for mains protection.

VII. BD2 is a Diac which provides the Triac with triggering pulses of square shape.

VIII. R1 and R2 are thermistors (temperature sensors) while R3 is a normal Resistor.

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Figure 3, Customized circuit diagram of TCFR 240V, 50Hz operation

3.5 Package Sample

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Figure 4 Showing a knock out box and a switch for packaging the TCFR after construction

3.6 Unit cost of TCFR

S/N Description of item Unit price (RM) Quantit

y

Amount (RM)

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

Inductor (L1)

NTC thermistor (R1)

PTC thermistor (R2)

Capacitor (C1, C2, C3)

Resistor (R3)

Triac BT 136

Diac DB2

Production of PCB

PVC knock out box

1-way double pole switch

Total

6.25

0.91

4.97

0.46

0.95

3.60

2.50

25.00

0.5

1.00

------

1

1

1

3

1

1

1

1

1

1

-----

6.25

0.91

4.97

1.38

0.95

3.60

2.50

25.00

0.5

1.00

46.97

After producing the PCB, the TCFR is mounted on a PVC or metallic knockout box which will

be covered with the double pole one-way switch. This may be installed on the wall surface or

mounted flush (wall recessed). However, for best performance, it is recommended to be surface

mounted so as to enable best performance of the temperature sensors.

The cost of one unit of the TCFR is approximately RM 47.00. However the cost can be

reduced to almost 50% when mass produced as the cost of electronic components is much

cheaper when purchased in bulk. The TCFR can compete favorably with the conventional fan

regulator which costs about RM 30.00.

3.7 Application of TCFR to Innovation Studies

I. The TCR is an innovation product as it provides a better way to solve a problem

(electrical energy saving, eases operation of fan, less fatigue and convenient).

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II. The TCR introduces entrepreneurship as it can be mass produced and marketed.

III. Society will benefit from it.

III.7.1 Area of Invention

The area of invention is Home and Office; appliance and comfort.

III.7.2 Kind of Invention

Labour saving; no need for manual changing/selection of fan speed, no fatigue and

inconvenience of leaving the bed of sofa/couch to change speed of fan.

III.7.3 General concept

Feedback principle; change in temperature causes change in resistance which in turn

changes the firing angle of a Triac to allow more or less current to flow and hence

controls the speed of the fan.

4.0 Conclusion

The design and construction of a temperature controlled fan regulator has been presented. The

TCR would adequately replace the existing conventional fan regulator for speed control of fans.

The TCR can be used to control the speed of ceiling fans, kitchen and bathroom exhaust fans and

wall mounted fans. By making the unit much smaller, it may be used to control the speed of

standing and table fans also. Therefore, the aim of attending the Innovation Studies class has

been achieved.

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References

[1] Walter Grondzik, Richard Furst, HVAC Components and Systems, Vital Signs Curriculum Materials Project.[2] http://www.wisegeek.com/what-is-a-ventilation-system.html.[4] Reznor, A., A Brief Explanation of ASHRAE Energy Efficiency and Ventilation Standards, White Paper.[3] Automatic Temperature Controlled Fan, Electronic Projects Vol. 19, P 189.

[5] Ahmad Faris Bin Zulkifli, Automatic Room Temperature Control with Security System,

B. Eng. Thesis, Universiti Malaysia Pahang, May, 2009.

[6] Alvasim P. A., Anumol R., Geo J., Nimmy Y., Pradeep K. V., Remote Controlled Fan

Regulator, B. Eng. Thesis, University of Calicut India, 2009.

[7] Hafiz Bin Nazar, Automatic Control Room Temperature Using PIC with LCD Display,

B. Eng. Thesis, Universiti Teknikal Malaysia Melaka, April 2009.

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[8] Muhammad Khairi Bin Abd. Ghani, Microcontroller Based Smart Fan

System, B. Eng.

Thesis, Universiti Malaysia Pahang, 2007.

[9] Nor Mazlee Bin Norazmi, Temperature Control System, B. Eng. Thesis,

Universiti Malaysia

Pahang, May 2009.

[10] http://www.rpc.com.au/information/faq/power-consumption/miscellaneous.html.

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