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Individual Engineering Project

EN0624

Project Planning Document

2018

Project Title:

Green Exhaust heat and Wind Energy Recovery System with Anti - haze Protection

Declaration

I hereby declare that the work contained in this dissertation has not been submitted for any other award and that it is all my own work. I also confirm that this work uses ideas and opinion from written papers and articles from the work of others.

Name: Lim Zi Yun

Signature: ______________________________

Date: 19th March 2018

Contents

1. Introduction ………………………………………………………………………………. 4

2. Aims and Objectives ……………………………………………………………………... 5

2.1 Aim …………………………………………………………………………………… 5

2.2 Objective ……………………………………………………………………………... 5

1. Literature Review ………………………………………………………………………… 5

3.1 Cooling Tower ……………………………………………………………………….. 5

3.2 Green Exhaust Air Recovery System …………………………………………........... 8

3.3 Air Purification System …………………………………………………………........ 8

1. Proposed Project …………………………………………………………………………. 9

4.1 Green Exhaust Air Recovery System …………………………………………........... 9

4.1.1 Wind Turbine …………………………………………………………………... 9

4.2 Air Purification System ……………………………………………………………... 12

4.2.1 Air Filter ………………………………………………………………………. 12

4.3 Air Quality Display System ……………..………………………………………...... 14

4.3.1 Arduino ……………………………………………………………………….. 14

4.3.2 Air Quality Sensor ……………………………………………………………. 15

4.3.3 Arduino I2O LCD Display ……………………………………………………. 16

1. Initial Design Work …………………………………………………………………....... 17

5.1 Product Appearance Design ……………………………………………………........ 17

5.1.1 Green Exhaust Air Recovery System ………………………………………… 17

5.1.2 Air Purification System ……………………………………………………….. 17

5.1.3 Overall Project Idea …………………………………………………………… 18

5.2 Product Circuit Design ……………………………………………………………… 19

5.2.1 Block Diagram ………………………………………………………………... 19

5.2.2 Flow Chart ……………………………………………………………………. 19

1. Project Management ……………………………………………………………………. 20

2. Project Plan …………………………………………………………………………....... 20

7.1 Gantt Chart ………………………………………………………………………….. 20

7.2 Costing ……………………………………………………………………………… 21

7.2.1 Prototype ……………………………………………………………………… 21

7.2.2 Commercial …………………………………………………………………… 22

7.2.3 Return On Investment (ROI) ………………………………………………….. 23

1. Summary of Progress/Work Required …………………………………………………... 23

2. References ………………………………………………………………………………. 24

1. Introduction

Singapore is situated near the equator and has a typically tropical climate, with high humidity and temperature. Wind in Singapore throughout the year shows a diurnal variation and is generally light. The mean surface wind speed is less than 2.5 m/s except during the presence of the Northeast Monsoon surge when mean speeds of 10 m/s or more have been observed [1] (Anon., n.d.). The minimum average wind speed for utility-scale wind power plants to generate electricity is 6 m/s (13 mph) [2] (Anon., n.d.). Thus, it is not suitable to use conventional wind turbines in Singapore to extract wind energy. However, harnessing wind energy from unusual wind sources may be one of the answers to generate electricity in Singapore. Due to the high temperature in Singapore, there are many large buildings such as schools and hospitals that have one or more cooling towers installed for building ventilation systems, thereby removing the heat from the buildings. A mechanical cooling tower is the most common type that relies on a power driven fan to draw the air through the tower. The wind speed at the outlet of the cooling tower is between 4m/s to 7m/s, so it is desirable to generate electricity.

Apart from this, Singapore also experiences haze yearly, because of the forest fires in her neighbouring country – Indonesia. According to the National Environment Agency, the highest Pollution Pollutant Standard Index (PSI) reading on record in Singapore is 401 (hazardous) in July 2013 [3] (Zenata, 2014). This hazard causes an increase in health problems in Singapore. The particles in the haze will affect the heart and lungs, especially in people who have chronic heart or lung disease. Based on the data for all reported cases of out-of-hospital cardiac arrests (OHCA) from 2010 to 2015 due to the air quality, the short to intermediate term risk of OHCA increased by 30% when the PSI level reached the unhealthy range which is exceeding 100 [4] (WY, 2017). Therefore, many buildings especially hospitals and schools in Singapore have started to install extra air purifiers to provide a cleaner air environment for patients and students.

The installation of air purifiers and cooling towers is the most imperative action that hospitals, schools and factories need, to improve the indoor air quality and health of the public. At the end of this project, a device that utilizes exhaust air from cooling towers to generate electricity that can, power up the air purification system, and sell back to the power grid will be created. The purpose of this project is to reuse the unwanted air from the cooling tower to generate electricity and create pollution-free air indoors, and at the same time, recoup money from the excess electricity.

1. Aims and Objectives

2.1 Aim

The aim of this project is to design a system to solve and illustrate the use of alternative sources of energy to generate electricity. At the same time, find out a technical solution to reduce the impact of the yearly haze on Singapore.

2.2 Objective

The objective of this project is to develop a system to recover exhaust air from mechanical cooling systems to generate extra electricity and at the same time, filter the inlet air. Apart from this, the grid system will allow users to sell the excess electricity that is generated by the wind turbine.

3.0 Literature Review

3.1 Cooling Tower

Generally, large buildings such as hospitals, schools and factories in Singapore install cooling towers for air conditioning systems or to cool down the indoor temperature and remove heat. Cooling towers use the process of evaporation to cool the water and transfer heat from the building into the atmosphere thereby reducing the indoor temperature.

Figure 1: Cooling Tower [5] (Anon., n.d.)

There are usually two types of cooling tower air flow designs that are classified as counter flow tower or cross flow tower. There are some differences between these two type of cooling towers and the differences are clarified in the table below:

In this report, a 656.2kW cross-flow square type cooling tower that is operated in Management Development Institute of Singapore was taken as a research object. The information and parameters of the cooling tower are given:

Brand: SHINWA Cooling Tower

Model: SDC-U250ASSD

Capacity: 656.2 KW

Water Flow: 1710 L/min

Inlet Temperature: 35 C

Outlet Temperature: 29.5 C

Wet bulb : 27 C

Fan Diameter: 2100 mm

Heat Transfer Area: 60 m2

Design Pressure: 1.05MPa (Tube Side); 1.6MPa (Shell Side)

Test Pressure: 1.35MPa (Tube Side); 1. 8MPa (Shell Side)

Work Pressure: 1.05MPa (Tube Side); 1.4MPa (Shell Side)

The wind speed of the cooling tower outlet is analysed by using anemometer with the help of M&E Supervisor, Mr. Chit Ko Ko and lab technician from School of Engineering, Mr. Razak. The readings that were measured by using an anemometer are recorded in the table below:

The observed cooling tower is a medium-sized cooling tower that supports a 15-floor building The wind speed range of the cooling tower outlet that was analysed is in between 4m/s to 7m/s which can be seen in the table above. At the same time, the rotating speed of the cooling tower exhaust fan also been measured by using a tachometer which is around 700rpm or 76.969m/s. According to the Fan Law and the fan rotating speed that had been measured, the power consumption of the cooling tower exhaust fan can be calculated as,

where,

P = Power Consumption

 = Air density = 1.225 kg/m3

N = Fan rotating speed = 700 rpm

d = Diameter of the fan = 2.1m

As the max power that can be generated by the wind turbine, which is showed in section 4.1, is 1.03kW, therefore the maximum power that can harvested from the wind at the cooling tower outlet is 6  10-6 % of the power consumption of the cooling tower exhaust fan.

3.2 Green Exhaust Air Energy Recovery System

The exhaust air recovery system was filed as a patent in 2011 [6] (Chong, et al., 2013) but it is currently not available in the market of Singapore. However, there are some articles available regarding the early development and design of the “Energy recovery wind turbine generator for exhaust air system”. Most of the article research were based on the design that can enhance the performance of wind turbines. A vertical axis wind turbine (VAWT) was chosen in the article and designed with an enclosure to mount it above the exhaust fan of a cooling tower to harness the wind energy to generate electricity [7] (Chong, et al., 1975). The use of VAWT in the articles is due to some advantages such as, not requiring the use of complicated devices for wind tracking, not directional, and works quietly. Thus, it is suitable for installation in residential areas [8] (Rahman, et al., 2015). However, VAWT is less efficient and causes drag due to the constant spin back into the wind. Therefore, a horizontal axis wind turbine (HAWT) is selected to use in this project. HAWT allows for blade-angle adjustment and it is directional, thus able reduce drag. The rotor blades of HAWT is able to pitch to a certain position to minimize damage but the cost of HAWT will be slightly higher than VAWT.

3.3 Air Purification System

Air purifier technology is already quite advances in the current market, but most of the purifiers are designed in stand-alone power systems. In this project, the purification system will be incorporated with the exhaust air energy recovery system, which means it will not consume electricity from the grid but from the battery that stores the electricity that is generated by the wind turbine. Apart from this, a mechanical filter will be used in the purification system of this project because it does not consume any electricity, thereby reducing the power consumption and at the same time being able to achieve the effect of purifying the polluted air. As most of the large buildings in Singapore, such as schools and hospitals, have existing air ventilation systems, therefore the purification system of this project is planned to fit into the mechanical filter at the front and back of the exhaust fan in the ventilation. There is another special feature available in the purification system of this project which is an air quality display system. The concentration of the particles in the air that have been purified will be detected and the LCD display will show the condition of the air quality to keep the users updated on the purification system and indoor air quality.

4.0 Proposed Project

4.1 Green Exhaust Air Energy Recovery System

4.1.1 Wind Turbine

The wind turbine is a renewable energy resource that works inversely to a normal fan. Instead of utilizing electricity and connecting with a motor to create wind, like a fan, wind turbines utilize wind energy and connects with a generator to generate electricity [9] (Anon., n.d.). The wind acts as a mechanical power to make the blades of the wind turbine turn and generate electricity. According to Betz Limit, no more than 59.3% of the kinetic energy from wind can be converted into mechanical energy [10 ] (Anon., n.d.). In theory, the actual power that is produced by the wind turbine can be calculated by using the formula below:

where,

P = Power (W)

CP = Power Coefficient = 0.59

 = Air Density (kg/m3)

A = Wind Turbine Swept Area (m2)

v3 = Wind Speed (m/s)

The average wind speed of the cooling tower outlet in MDIS that was measured by the anemometer which was mentioned in section 3.1 is around 6m/s. The density of air will be varied according to the surrounding temperature. The outlet temperature of the cooling tower was 29.5 C, therefore the air density was around 1.165 kg/m3 which can be refer to from figure 2 below. A wind turbine with a blade length of 2.1m is planned to be used in this project, so the input and output power of the wind turbine can be calculated by using the previous formula:

Figure 2: Air Density Table [11] (Anon., n.d.)

Apart from this, the amount of electricity that can generated by a wind turbine will vary due to the wind speed, power efficiency, blade length and angle. Therefore, an experiment about the effect of blade angle on power generation in wind turbines was carried out to observe the perfect blade angle for wind turbine. A 500W wind turbine model with blade length of 0.325m that is available in MDIS lab was used as the experiment object and the table fan with the highest wind speed was also used in this experiment to act as a wind source for wind turbine. The experiment results are recorded in the table below:

Test 1: Blade angle pitch in 20

Test 2: Blade angle pitch in 35

Due to some avoidable systematic and human error, the readings may not be very stable and perfect, but it still shows that a wind turbine with 35 of blade angle have a higher generated output power. Based on the results of a project that is available online which is showed in figure 3 below, it proves that the results of the experiment that was carried out in the MDIS lab is on the right track. However, the optimal blade angle for the wind turbine of this project will be designed and mentioned in greater detail in the final report.

Figure 3: Results of Blade Angle Effect Test [12] (Anon., n.d.)

As a result of the high wind speeds at the cooling tower outlet, a wind turbine will be used for the exhaust air energy recovery system of this project. It will be used to generate extra electricity by utilize the exhaust air that flows out with a high speed from the upper tower or outlet of the cooling tower.

Figure 4: Horizontal Axis Wind Turbine [13] (Anon., n.d.)

4.2 Air Purification System

4.2.1 Air Filter

There are different kind of mechanical air filters are currently available in the market. The size of particles that can be trapped by the filters are based on the density of its mesh. Each type of filter has its different strengths and weaknesses. A few types of the most common air filter is listed in the table below with diagram.

As a result, the mechanical air filter that will be used in the air purification system of this project is the high-efficiency particulate air filter which is also known as HEPA filter. The fine mesh (shown in the figure 8 in the table above as white surface part) of the HEPA filter can trap up to 99% of harmful particles that are sized two microns or larger, such as pet dander, smoke and dust [18] (Anon., 2014)]. These particles are very tiny but large enough to cause heart and lung disease. HEPA filter is the most efficient filter in the table above to trap the harmful and fine particles.

4.3 Air Quality Display System

4.3.1 Microcontroller

Arduino microcontroller board is an electronic platform that is able to read the input and monitor the output to functions based on the program that is uploaded into the Arduino via default IDE software. There are different kinds of Arduino boards with variations of RAM size, that are able to support different sized circuits, the table below shows the comparison of the Arduino board.

In this project, Arduino Uno will be used because it is sufficient enough to support the display system. It will act as the brain or CPU to control the air quality display system.

4.3.2 Air Quality Sensor

Air quality sensors are a kind of device that detects the presence of harmful particles in the surrounding area and monitors the concentration of harmful particles such as sulphur dioxide (SO2), carbon monoxide (CO), nitrogen dioxide (NO2) and ozone (O3). The surrounding air quality index (AQI) is scaled based on the pollutant concentration and also classified into different levels of health concern which is shown in the table below:

The air quality sensor will be used to determine or detect the concentration of harmful particles in the air that have been purified and display the surrounding air quality on LCD screen to let the users know.

Figure 12: Air Quality Sensor [22] (Anon., n.d.)

4.3.3 Arduino I2C LCD Display

The I2C which also known as Inter-Integrated Circuit is a multi-master, multi-slave, single-ended and serial computer bus that was invented by Phillips in 1982 [23] (Anon., n.d.). It is normally used to attach the lower-speed peripheral ICs with the processors and microcontroller, for instance, the Arduino in short distance intra-board communication. A standard 162 LCD will need at least 6 input pin to connect with the microcontroller to talk or program it. However, the with the LCD module connected with the I2C interface, it will only need two connections to display the information. The I2C has to be attached at the back of the LCD module that have a HD44780 compatible interface [24] (Hareendran, 2016) so that it only needs two cables to connect the LCD with Arduino. The LCD that connect with I2C will make the programming easier, as it does not need to be programmed bit by bit to display the statements. In this project, the quality level of the air that had been purified will be detected by the air quality sensor and displayed on the I2C LCD screen to let the users rest assured of the indoor air quality.

Figure 13: I2C LCD Display [25] (Anon., n.d.)

5.0 Initial Design Work

5.1 Product Appearance Design

5.1.1 Exhaust Air Energy Recovery System

The figure 14 below shows the initial design of the exhaust air energy recovery system in this project. Due to the high wind speed at the outlet of the cooling tower, the wind turbine is designed to be placed at the upper tower or outlet of the cooling tower.

Figure 14: Top View of Wind Turbine in Cooling Tower

5.1.2 Air Purification System

Figure 15 below shows the initial design of the air purification system in this project. The air filter is designed to fit in the pipe of existing air ventilation systems that already available in most buildings. The exhaust fan in the ventilation system will suck the outdoor air into the building and the harmful particles will be trapped by the filter simultaneously while the air passes through it.

Figure 15: Air Purifier Design

5.1.3 Overall Project Idea

Figure 16 below shows the design of the whole system for this project. Around 60% of power that is generated by the wind turbine from the exhausted gas or air of the cooling tower will be sent to the power grid and the remaining 40% of power will be stored inside the battery due to its instability. The air filters that are used in this project are mechanical filters, therefore it will not consume any electricity. However, the air quality sensor and LCD display screen in the air purification system will be powered by the electricity that is stored in the battery to detect and display the air quality.

Figure 16: Overall System Design

5.2 Product Circuit Design

5.2.1 Block Diagram

The block diagram below (figure 17) shows the overall process of the green exhaust wind recovery system with air purification system.

Figure 17: Block Diagram

5.2.2 Flow Chart

The electricity that is generated by the exhaust wind recovery system will be used to power the LCD and air quality sensor in the air purification system to detect and display the quality of air that had been purified. The program, based on the flow chart below, (figure 18) will be uploaded into the Arduino Uno to control the air quality display system.

Figure 18: Flow Chart

6.0 Project Management

The project management can be compartmentalized into two stages,

Stage 1:

- background study and research

- initial product design

- complete the project planning report writing

Stage 2:

- determine and buy components

- finalise hardware and software design

- complete the final report writing

- final presentation (poster)

7.0 Project Plan

7.1. Gantt Chart

The figure 19 below shows the time management of this project.

Figure 19: Gantt Chart

Done (Stage 1)

In Progress (Stage 2)

Not Yet Starts (Stage 2)

7.2 Costing

7.2.1 Prototype

The minimum build cost for the prototype of this project is roughly estimated based on the shopping website – BangGood. The overall price of the components that needed to use in the prototype of this project are listed in the table below.

As a result, the estimated build cost of the prototype for this project is around S$379.30. The final prototype build cost may vary due to some adjustment during the prototype assembly and testing.

7.2.2 Commercial

The minimum commercial build cost of this product is roughly calculated in the table below:

As a results, the estimated commercial build cost for this project is around S$4888.73. However, the final build cost may be varied due to some alter after further research and investigate.

7.2.3 Return On Investment (ROI)

Based on the electricity tariff of SP Group from 1 Jan to 31 March 2018, the cost of electricity is 21.56 cents per kilo -Watt hour. If 60% of electricity that generated by the wind turbine is sent back to the grid and sold to SP Group, the break-even of this product can be calculated:

Electricity tariffs = 21.56 cents/kWh

Average power generated by wind turbine = 24.72kWh per day

Average power generated per month = 24.72kWh  30 = 741.6kWh per month

40% stores in battery for DC load = 741.6kWh  0.4 = 296.64kWh per month

Money saved per month from 40% power = 296.64kWh  21.56 cents/kWh

= 6395.5584 cents

 S$ 63.95

60% send to utility grid system = 741.6kWh  0.6 = 444.96kWh per month

Money earned per month from the 60% power = 444.96kWh  21.56 cents/kWh

= 9593.3376 cents

 S$ 95.93

months  4 years 3 months

In conclusion, this product can save up to S$ 63.95 of electric bills per month and at the same time, also able to earn up to S$ 95.93 per month by the sale of extra generated electricity. As the lifespan of a wind turbine is around 20 to 25 years, users might start to make profit from this product after 4 years 3 months.

8.0 Summary of Progress/Work Required

The progression or working of this report can be summarized as:

1. Literature survey

2. Concept design

3. Components selection

4. Circuit design and testing

5. Programming

6. System integration

7. On-site testing

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2. Anon., n.d. The most frequently asked questions about wind energy (circa 2001-2004). [Online]
   Available at: http://www.culturechange.org/wind.htm
   [Accessed 1 March 2018].

3. Zenata, P., 2014. The Effects of Haze on Health, the Economy and the Environment. [Online]
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4. WY, A. N., 2017. Haze brings risk of cardiac arrests: Study. [Online]
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6. Chong, W. T., Yuen Yoke , K. & Fazlizan Abdullah , A., 2013. Wind and exhaust air energy recovery system. Malaysia, Patent No. WO2013073930A1.

7. Chong, W. et al., 1975. Early development of an energy recovery wind turbine generator for exhaust air system. Applied Energy, January, 112(2013), pp. 568-575.

8. Rahman, A. A. A., Yahaya, N. A., Bahsan, R. & Ahmad, U. K., 2015. Energy harvesting from cooling tower by vertical axis wind turbine (VAWT). Jurnal Teknologi (Sciences & Engineering), 15 February, 76:5(2015), pp. 37-41.

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16. Anon., n.d. 12" x 12" x 2" Pleated Media Filter, MERV-8. [Online]
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23. Anon., n.d. I²C. [Online]
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24. Hareendran, T., 2016. Arduino I2C LCD Backpack Introductory Tutorial. [Online]
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25. Anon., n.d. SainSmart IIC/I2C/TWI 1602 Serial LCD Module Display for Arduino UNO MEGA R3Blue on White. [Online]
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