Automotive Fuel Cell Systems

April 2, 2010

Patrick Blake

Adolescence is that difficult period of time when carefree children transition to responsible adults… we hope. That is the goal, after all, for teens to develop into mature, productive, responsible members of the community. One method for assisting this transition is obtaining part-time employment. A job can help teenagers better develop their identities, obtain increased autonomy, achieve new accomplishments, develop work experience, and become more independent from their parents.

According to the U.S. Department of Labor, 50 percent of American teenagers hold informal jobs, such as babysitting or yard work, by age 12. Boys tend to begin their jobs at younger ages and work more hours than girls. By age 15, nearly two-thirds of American teens have had some kind of employment. By the time teens graduate from high school, 80% will have held a part-time job at some time during the school year. The average high school student works 20 hours per week, and about 10% work full time (35 hours or more).

There are many obstacles to teens obtaining employment. Finding reliable transportation is critical, and that can be difficult if the job is not close by and the teen’s parent(s) work. Fighting stereotypes that employers have about adolescents, such as poor attitudes or lack of skills, can be challenging. In this particular economy, there aren’t very many job opportunities for teens.

Teens want to work for a variety of reasons, but more than half report their involvement in work is motivated by the desire to buy things. Typically, teens spend their money on car expenses, recreational expenses, clothing, educational expenses, saving for college, and helping their families with living expenses (e.g., rent, groceries).

Researchers have studied and debated the benefits and drawbacks of teens and part-time jobs for more than 2 decades. Many researchers, including those on government panels like the National Commission on Youth, praise part-time work and say it contributes to the transition from youth to adulthood. Other studies have found significant negative consequences to students working over 20 hours a week. We will take a close look at both.

Benefits of Teens Holding a Part-Time Job

There are many benefits to adolescents obtaining employment, including:

· Obtain valuable work experiences, which are excellent for a resume.

· Learn how to effectively manage finances. Even if the teen is simply using their earnings to pay for their own expenses, they will learn to budget between clothes, movies, and car expenses.

· May provide networking possibilities and set a child on a rewarding lifetime career path.

· Provide constructive use of free time. An after-school job can also provide adult supervision, especially if you work longer hours than those in a typical school day. Employment gives teens less time to engage in risky behaviors.

· Learntimemanagementskills.

· Formgoodworkhabits.

· Gain useful, marketable skills such as improving their communication, learning how to handle people, developing interview skills and filling out job applications.

· Instill new confidence, sense of responsibility and independence.

Drawbacks of Teens Holding a Part-Time Job

There are also negative consequences of teen employment that may outweigh the positive benefits, such as:

· Less time for homework. Working students may not have or make the time to complete their work.

· Higher rates of absenteeism and less school involvement. Employment may place constraints on the student’s study and sleep time. Fatigue or lack of preparation for the day’s academic activities may discourage the working teen from going to school and a job may take the place of extracurricular activities.

· Lower grades in school. Students who work more than 20 hours a week have grade point averages that are lower than other students who work 10 or less hours a week.

· More likely to use drugs and alcohol. Research suggests that substance abuse is higher for students who work 20 or more hours per week.

· Development of negative views of work itself. Early entry into a negative or harsh work environment may encourage negative views of work. This would depend greatly on the maturity level of the teenager and the type of job obtained.

· Increased stress. Balancing work and school can prove to be too much for any student.

Research seems to suggest that students that work 10 hours or less a week gain the benefits of employment, while students that work over 20 hours a week suffer the negative consequences of work mentioned above. Other factors that affect how students handle employment and school life include the intensity and difficulty of the work done.

Summer Employment

Summer employment is an excellent alternative, as it does not interfere with schooling and provides teens with a constructive use of their free time. It allows adolescents to garner all the benefits of employment without overtaxing their busy school schedules. Teens should begin looking for summer employment during Spring Break. Possible jobs for teens are: landscaping, delivering newspapers, babysitting, retail stores (such as grocery stores or clothing stores), movie theaters, working at a theme park, being a camp counselor, lifeguarding at a pool, and dog walking.

Work Requirements

The U.S. Department of Labor sets the minimum age for employment at 14. It also limits the number of hours worked by minors under the age of 16. However, minimum age requirements do not apply to minors employed by their parents or guardian. Youths of any age may also deliver newspapers; perform in radio, television, movie, or theatrical productions; and babysit or perform other minor duties around a private home. Laws regulating employment of minors vary among states and U.S. territories, for example, many states require youth to obtain an employment and/or age certificate prior to being hired. Many times these certificated are issued by the school, but you should contact your state’s Department of Labor for more information.

How Parents Can Help Working Teens

Before your teen applies for employment, be sure to discuss the pros and cons with him or her, as well as the responsibilities associated with a job. You may also want to agree to a job on a trial basis, such as “you can work x number of hours a week this grading period and then we will decide if you can keep working, based on your grades.” There are several things that you as a parent can do for your teen to help ease the stress associated with juggling school, work, and family life:

· Come to a consensus about how you expect your teen to use his or her income. Will they be helping out with family finances? Would you like them to begin saving for college? Reaching a consensus will help to avoid later conflicts about money. Prepare a budget with your child, setting limits on spending and enforcing a percentage-of- paycheck-into-savings policy with which you’re both comfortable.

· Create a daily or weekly schedule with your teen that highlights the time that they spend working and the time they spend on homework and other school-related activities.

· Set up family time periodically. This could be once a week or month and is a time where you and your teen can reconnect through conversations, game playing, or family outings.

· Teach your teen practical ways to manage adverse situations on their jobs as well as in school.

· Teach your teen effective ways to manage the many demands that are made on their time. As they move closer to adulthood it will be necessary to manage many demanding roles as their responsibilities increase. This is a good time to learn how to use their time and resources wisely.

· Mostimportantly, besupportive.

Part-time jobs can be a wonderful experience, with the right supervision and parental guidance.

Automotive Fuel Cell Systems

Ivan Surovtcev, ViktoriiaLeukhina

Ivan Surovtcev, SPbETUmaster student, i.surovtsev.work@gmail.com

ViktoriiaLeukhina, SPbETUmasterstudent,v.leukhina@yandex.ru

Abstract

The article describes what is a fuel cell, internal structure of a cell and main operational principles, fuel cell performance characteristics and loses are also described.Fuel cell applications (in automotive and non-automotive systems) are listed, some examples are given. The paper also describes comparison with electric vehicle’s battery types (lead acid, NiMH and Li-on)and with conventional vehicles; benefits and disadvantages of using fuel cells are learnt.In the past, fuel cells were large and extremely expensive to manufacture, just as the first calculators and computers were. But, just like these products, the cost of fuel cells will quickly come down to consumer-affordable levels with mass production.Basic fuel cells running on pure hydrogen are pollution free, giving off only electricity, water, and heat.Economically, fuel cells represent a prudent path to provide the country's electric power because they can be installed quickly, are fuel flexible, and can be put in place incrementally, mitigating the need for more costly and sweeping changes.

Key words: fuel cell, automotive industry.

1. Introduction

A fuel cell is an electrochemical energy conversion device that converts hydrogen and oxygen into electricity, heat, and water. It is very much like a battery that can produce electricity while being recharged continuously. [1]

Although today's high-tech fuel cells hardly resemble their forefathers, the process upon which fuel cells are based has been known to science for more than 100 years. The first fuel cell (or "gas battery" as he called it), was invented by William Robert Grove in 1839, only 39 years after Alessandro Volto invented the battery (the voltaic cell).[1]

Fuel cell converts chemical energy in fuels into electrical energy directly, promising power generation with high efficiency and low environmental impact. Because the intermediate steps of producing heat and mechanical work typical of most conventional power generation methods are avoided, fuel cells are not limited by thermodynamic limitations of heat engines such as the Carnot efficiency. In addition, because combustion is avoided, fuel cells produce power with minimal pollutant. [2] These criteria are very attractive for automotive industry.

2. Fuel cell’s operation principles

2.1 Unit fuel cell

Unit cells form the core of a fuel cell.. The basic physical structure, or building block, of a fuel cell consists of an electrolyte layer in contact with an anode and a cathode on either side. Figure 1 describes this.

Schematic representation of a unit cell with the reactant/product gases and the ion conduction flow directions through the cell is shown in the figure 2, below.

Fig. 1 - Basic structure of a unit fuel cell

Fig. 2 – Description of internal processes

In a typical fuel cell, fuel is fed continuously to the anode (negative electrode) and an oxidant (often oxygen from air) is fed continuously to the cathode (positive electrode). The electrochemical reactions take place at the electrodes to produce an electric current through the electrolyte, while driving a complementary electric current that performs work on the load.

2.2 Fuel cells system

But, of course, unit fuel cell or even stack of fuel cells is not enough for building up power system. In addition to the stack, practical fuel cell systems require several other sub-systems and components (see figure 3); the so-called balance of plant (BoP). Together with the stack, the BoP forms thefuel cell system[2]:

Fuel preparation.Except when pure fuels (such as pure hydrogen) are used, some fuel preparation is required. [2]

Air supply.This includes air compressors or blowers as well as air filters. [2]

Thermal management.All fuel cell systems require careful management of the fuel cell stack temperature. [2]

Water management.Water is needed in some parts of the fuel cell, while overall water is a reaction product. To avoid having to feed water in addition to fuel, and to ensure smooth operation, water management systems are required in most fuel cell systems. [2]

Electric power conditioning equipment.Since fuel cell stacks provide a variable DC voltage output that is typically not directly usable for the load, electric power conditioning is typically required.[2]

Fig. 3 - Energy conversion in Fuel cells system.

Date: 2014-12-29; view: 1124