DESIGN ANALYSIS OF A MANUALLY OPERATED FOOT (PEDAL) AIR PUMP

DESIGN ANALYSIS OF A MANUALLY OPERATED FOOT (PEDAL) AIR PUMP

ABSTRACT

Pumps are devices that are used whenever fluids (liquid or gases) or sometimes slurries are to be moved by mechanical mechanism or action. This project centers on the design of an air pump which is operated by using a foot, through the aid of a pedal, to force air through a discharge tube into a vacuum. The principle of operation of this pump is similar to that of the popular hand air pump with the physical structure being the most significant difference hence the name, “MANUALLY OPERATED FOOT AIR PUMP”. In the course of this project, parameters such as mass flow rate of air through the nozzle of the discharge tube and pressure of air at the nozzle of the discharge tube were considered for the design. After the design analysis, the result was used to evaluate the performance of this pump. It shows that the efficiency of the pump was greatly depends on the properties of spring used and the pump was relatively inexpensive if it will be fabricated.

CHAPTER ONE

1.0       INTRODUCTION

1.1        BACKGROUND

Pumps are devices that are used whenever fluids (liquid or gases) or sometimes slurries are to be moved by mechanical mechanism or action. The study of pump is a very large scope on its own however, we will be dealing particularly with air pumps.(fao.org, 2011)

A reciprocating air pump is a positive displacement pump which is used to inflate tires, ballots, balls etc. Hence reciprocating air pumps are generally useful whenever the transfer of a gas, usually air is desired. Air pumps vary in shapes, sizes and tasks. Even though they generally commonly pump air, some may have a very little similarity or more as the case may be. However, they are essential tools used in everyday life. Perhaps, without them, a little portion of life’s simplicity would have been lost.(Black, 2003).

The first air pump known as the spool vacuum air pump was invented in the year 1649 by Otto Von Guericke which was later called air pump in the 19^th century. Robert Hooke made the first effective air pump for scientific purposes for Robert Boyle in England in 1658 (George Wilson, 1849).

Air pumps can be placed into different categories depending on:

• Method of operation and
• Principle of operation

The classification base on the method of operation includes:

1. Manually operated air pumps (as will be referred to simply as manual air pump) and
2. Automatic (motor) powered air pumps (or simply automatic air pump).

Those which are manual often require pumping by hand, arm or foot (as in this project). They use human power and mechanical advantage to move fluid from one place to another while the automatic pumps run off some sort of other power sources, mostly electricity. The latter are always easy to operate and offer more efficiency but the formal have the advantage of portability, least cost of production to name a few.

We can see the applications of these pumps firstly, the automatic air pumps in aquarium and in ponds to diffuse oxygen into the water to make it more inviting and for animal life and in the area of septic systems which employs an aerobic process to use bacteria to accomplish the goals of removing and/or reducing the amount of solids in the system. And secondly the manual air pumps which find various applications in inflating vehicles and motorcycles in rare occasions and mostly bicycles tires and footballs.

Classification of pumps based on the principle of operation includes:

• Positive displacement pumps
• Rotodynamic pumps

In positive displacement pumps, fluid is drawn or forced into a finite space bounded by a mechanical parts and is then sealed by some mechanical means. The fluid is then allowed to flow out from the space and the cycle is repeated. Thus, in a positive displacement pump, the fluid is intermediate or fluctuating. The flow rate of the fluid is governed by the dimensions of the space in the machine and by the frequency with which it is filled or emptied.(Amadu, meen 512, 2016)

In the rotodynamic type, there have a rotating element through which the fluid passes (such element is called an impeller)

Hence, from the classifications above, the present project- manually operated foot air pump can be classified as a “manually operated positive displacement foot air pump”.

1.2        STATEMENT OF THE PROBLEM

Man’s continuous search for better ways to make life simpler seems to be an unending mission. It is in this light that the decision to improve the manually operated foot air pump arose. Also, in the same quest for an easier life, man strives to substitute for the barely unavailable sources of power, expensive materials related with automatic air pumps.

The correct tire pressure is crucial to the safe operation of a vehicle (a car, motorcycle and bicycle) but many owners do not check the air pressure of their tires before hitting the road. This may be partly perhaps because of the stress it takes to check the pressure and fill the tire; is never very fun no matter how you look at it: kneeling down on the rough ground against your bare kneels, fumbling around trying to attach the tire air pump to the valve stem are all parts of the routine. Moreover, the difficulty in reaching the valve stem of some vehicles can be a discouraging factor in carrying out the necessary and frequent check.

Having a less complicated and a work-easing device (air pump) i.e. one which fits into our above mentioned goals could be the solution to the tedious and undesirable routine.

Electrically operated air pump would have been the best option for such a device but its general bulkiness, heavy weight and added complication of the electrical connection make it unsuitable for use.

1.3              AIM AND OBJECTIVES OF THE PROJECT

This project aims at analysing, the design and evaluating the performance of a manually operated foot air pump for footballs, bicycles and motorcycles with improved efficiency. The specific objectives include

1. To carry out the design analysis of the pump.
2. To carry out the performance evaluation of the pump.
3. To estimate the cost of the pump.

 1.4      SIGNIFICANCE OF THE PROJECT

The project of discussion relates to a manually operated air pump, in particularly, a manually operated foot air pump. This project provides a manually operated foot air pump, as it will be subsequently referred to as simply “foot pump,” that uses a foot to transfer almost the same volume of air to a pneumatic tire as its hand operated pump counterpart with an additional balance and comfort as bonuses. There are just very few modifications of the hand operated pump which are mostly structural. Almost every working principle is common to both pumps.

1.5       SCOPE AND LIMITATION

This project requires only the use of mechanical operations. The use of electrical supply or any other source of energy such as solar or fuel is not necessary hence, maintenance and capacity costs are very low and affordable.

DESIGN AND IMPLEMENTATION OF AC TO DC CONVERTER

DESIGN AND IMPLEMENTATION OF AC TO DC CONVERTER

Abstract

Several research activities at KTH are carried out related to Isolated AC/DC converters in order to improve the design and efficiency. Concerning the improvement in the mentioned constraints, losses of the elements in the prototype converter are modeled in this thesis work. The obtained loss model is capable of calculating the losses under different circumstances. The individual contribution of losses for each element at different conditions can be obtained, which is further useful in improving the design and therefore, efficiency. The losses in different elements of the converter, including power semiconductor devices, RC-snubbers, transformer and filter inductor at different operating points can be computed by using the obtained model.The loss model is then validated by comparing the analytical results with the measurements.The results based on developed loss model show consistency with the measured losses. The comparison at different conditions shows that, the difference between measured and analytical results ranges between10% to 20 %. The difference is due to those losses which are disregarded because of their negligible contribution. On the other hand, it is also observed that if the neglected losses are counted, the difference reduces up to 10%.

Chapter 1 – Introduction

1.1            Introduction

The thesis deals with the power loss modelling of “Two Stage Isolated AC/DC Converter” which is suitable for sustainable energy sources. This chapter provides a base for all material presented in the next chapters, which focuses on the loss modelling of different elements in the prototype converter.

AC to DC Converters are one of the most important elements in power electronics. This is because there are a lot of real-life applications that are based on these conversions. The electrical circuits that transform alternating current (AC) input into direct current (DC) output are known as AC-DC converters. They are used in power electronic applications where the power input a 50 Hz or 60 Hz sine-wave AC voltage that requires power conversion for a DC output.

The process of conversion of AC current to dc current is known as rectification. The rectifier converts the AC supply into the DC supply at the load end connection. Similarly, transformers are normally used to adjust the AC source to reduce the voltage level to have a better operation range for DC supply.

1.2            Background and Justification

The thesis is related to the power loss modelling of the two stage isolated AC/DC converter. The power loss modelling of the power electronic converters is of vital importance because of its relation with efficiency, reliability, cost and size.

The prototype converter comprises a Voltage Source Converter (VSC) and a converter coupled by a medium frequency transformer, which are studied in this thesis. The prototype can be operated by applying the soft-switched commutation across all the valves at all the operating points leading to lower switching losses of the power semiconductor devices. The valves of the VSC in the prototype are equipped with lossless snubbers that reduce the

switching losses across the IGBTs and the diodes. The converter in the prototype is equipped with RC-snubbers to reduce the stress on the valves during the commutation and other transients. Furthermore the medium frequency transformer has also lower losses because of its compact size. The concepts applied to the prototype are useful in loss reduction and further can result in higher efficiency and ultimately power density which are the main goals in the design of power electronic converters.

Despite the fact that various loss minimization techniques are employed, the prototype suffers lower efficiency at lower output power. There can be a number of reasons. In order to resolve the issue, power loss modelling of the prototype is required. After obtaining the proper loss model, the losses across the individual elements in the prototype can be obtained, which further helps in improving the design and efficiency.

Alternating current (AC) Alternating Current In alternating current, the current changes direction and flows forward and backward. The current whose direction changes periodically is called an alternating current (AC). It has non-zero frequency. It is produced by AC generator.

Direct Current (DC) Direct current, the current doesn’t change its magnitude and polarity. If the current always flows in the same direction in a conductor then it is called direct current.

1.3    Aim and Objectives of Project/Research

1.3.1     Aim

1. The aim of the project is to implement a AC to DC inverter system.

1.3.2     Objectives

1. To design a ac to dc inverter system.

2. To construct a device that can efficiently change ac voltage to dc voltage level to another within power network.

3. To develop a step down inverter with single input voltage.

4. To be able to describe the losses in all the element that in converted..

1.4            Motivation

AC signals can’t be stored and DC power can’t be stored so we need to convert AC to DC. To convert the electrical energy into DC, we need to store it. AC can be transported over long distances because of it’s frequencies.

1.5     Contribution to Knowledge

Electricity flows in two ways: either in an alternating current (AC) or in a direct current (DC). Electricity or “current” is nothing but the movement of electrons through a conductor, like a wire. The difference between AC and DC lies in the direction in which the electrons flow.

1.6Scope and Limitation of project

Scope

project will make use of technology called Beat Frequency Oscillator (B.F.O). this technology employs two oscillators at resonance and a variation of the frequency.

Limitation

(i) Alternating voltages cannot be used for certain applications e.g. charging of batteries, electroplating, electric traction etc.

(ii) At high voltages, it is more dangerous to work with AC than DC.

You are required to state categorically the coverage and limit of the project.

You are required to state categorically the coverage and limit of the project.                 

1.7Structure of the Report

• Chapter 2 will look at literature and operation of the converter considering the losses are explained in this chapter.
• Chapter 3 This involve adopting engineering methodology to calculate the losses are explained in this chapter. Apart from this the mathematical description and the formulation of the losses is also presented.   
• Chapter 4 This discuss test result of the losses in each element of the converter. The effects of variations of different parameters on the losses are presented.
• Chapter 5 The conclusion, project appraisal, and recommendation.

FACTORS AFFECTING COST OF CONSTRUCTION IN NIGERIA

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FACTORS AFFECTING COST OF CONSTRUCTION IN NIGERIA

CHAPTER ONE

1.0       Background of the study

The growing need for construction of all types coupled with a tight monetary supply has provided the construction industry with a big challenge to cut cost.  According to Mendelson and Greenfield (1996) the remaining part of the twentieth century would involve corporations, institutions and government in a race to survive. The attendant dwindling economic fortune of nations economies around the World have geared up the participant in these sectors (the client in particular) to take up the challenge of ensuring efficient use of their resources to obtain value for money in terms of performance.

 

The total cost of construction in normal circumstances is expected to be the sum of the following cost: Materials, Labour, Site Overheads, Equipment/Plant, Head office Cost and Profit but in many parts of the world particularly in Nigeria, there are other costs to be allowed for.

These costs according to Mbachu and Nkado (2004) have obvious negative implications for the key stakeholders in particular, and the industry in general. To the client, high cost implies added costs over and above those initially agreed upon at the onset, resulting in less returns on investment. To the end user, the added costs are passed on as higher  rental / lease costs or prices. To the consultants, it means inability to deliver value – for – money and could tarnish their reputation and result in loss of confidence reposed in them by clients. To the contractor, it implies loss of profit through penalties for non- completion, and negative word of mouth that could jeopardize his/her chances of winning further jobs, if at fault.

The proposed work will investigate and report the other costs to be allowed for, which are the basic factors affecting construction cost in Nigeria and also proffer solutions to how construction cost can be minimized.

1.1       Statement of the Problem

The demand for more construction of all types, coupled with a tight monetary supply has provided the construction industry with a big challenge to cut costs. The problem of high contract costs of all aspects of construction is becoming obvious. Consequently, substantial increases are being observed in projects.  This substantial increase has brought about loss of client confidence in consultants, added investment risks, inability to deliver value to clients, and disinvestment in the construction industry.

 

1.2       Aim and Objectives of the study

The aim of the study is to find out the factors affecting construction cost in Nigeria and proffer solutions to how construction cost c an be minimized.

The objectives of the study are as follows:

1. To identify the main factors affecting construction cost in Nigeria.
2. To determine the severity rank of the factors amongst clients, consultants and contractors.
3. To determine the agreement ranking factors between clients, consultants and contractors.
4. To proffer solutions on how to minimize construction cost in Nigeria.

  1.3       Research Hypotheses

To test the hypothesis:

1 (a). Ho: Contractors and Clients do not generally agree on the severity rank of the factors affecting construction cost in Nigeria

1 (b). H1: Contractors and Clients generally agree on the severity rank of the factors affecting construction cost in Nigeria

2 (a). Ho: Clients and Consultants do not generally agree on the severity rank of the factors affecting construction cost in Nigeria

2. (b) H1: Clients and Consultants do not generally agree on the severity rank of the factors affecting construction cost in Nigeria
3. (a) Ho: Consultants and Contractors do not generally agree on the severity rank of the factors affecting construction cost in Nigeria
4. (b) H1: Consultants and Contractors generally agree on the severity rank of the factors affecting construction cost in Nigeria

 

1.4       Significance of the study

An assessment of the study would enable Clients, Contractors and Consultants give an economic approach to construction work such that they would be able to identify the dominating factors leading to high construction cost in Nigeria.

The application of the solutions proffered to minimizing construction cost would restore client’s confidence in consultants, reduce investment risks, and generally boost the viability and sustainability of the industry

 

1.5       Scope and Delimitations

The scope of this research is limited to identification of essential factors affecting construction cost and proffering solutions on how to reduce construction cost in Nigeria.

The study is limited to projects in the Lagos metropolis of Nigeria because there is easy access of information in the Lagos metropolis by the researcher.

Target respondents for this study are the principal actors in the construction industry namely: the Client, the Consultant and the Contractor.

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