Day 1: Energy Convertors Intro Read pp.2-8 and take your own note on the

following: What is an energy converter? Are they 100% efficient? Why or why not? List 4 different types/examples of energy converters What energy systems do energy converters appear in? Why is efficiency so important in energy conversion? How is efficiency calculated? Name 1 advantage and 1 disadvantage of energy

conversion. List 1 example of energy conversion from the device

you built for your 9wk test.

Mechanical Energy Convertors

• change mechanical energy to useful fluid, thermal, or electrical energy• input energy is different from output energy (hence convertor)• if input energy type same as output energy type = force transformer

What Do They Do and How Different from a Transformer?

Mechanical Energy

Energy Convertor

Fluid Energy

Electrical Energy

Thermal Energy

Vane pump Alternator Spin Welder

Mechanical Energy Convertors

Many times, rated values for devices must be converted to common energy units

* WHEN ENERGY IS AVAILABLE WORK CAN BE DONE. •WHEN WORK IS DONE, ENERGY IS OFTEN PRODUCED• Therefore Energy=Work or E=W

Common Conversion Factors for Energy Units

• are based on type of energy output (ex. water pump output is fluid pressure ,so fluid pressure units are used….65psi)• common energy convertor units based on output type are listed below:

Energy Output

English SI

Mechanical ft.lb, HP, Watts (W) N.m, Watts (work)Fluid ft.lb, psi,

gpm,ft3/min (flow rates)

N.m, N/m2, l/min, cm3/sec (flow rates)

Electrical J (joule) J (joule), Watts(W)Thermal BTU, BTU/hr Cal, Cal/sec

Convertor Energy Units

Mechanical Energy Convertors

• takes a mechanical energy input and converts it into useful fluid energy output• check out the VANE PUMP below

What’s a Mechanical To Fluid Energy Convertor?

Low Pressure Water In (2psi)

High Pressure Water Out (500psi)

Gas powered rotating vanes/blades

*Rotational mechanical energy IN(blades) is converted to fluid kinetic energy OUT(water) use to move water out of an area (ex. broken water line)

Foot pump* is another good example (input=mechanical , output=fluid(air)) *Demo

BeltAlternator Shaft

Rotational mechanical energy IN(belt,alternator shaft)

Mechanical Energy Convertors

• takes a mechanical energy input and converts it into useful electrical energy output• check out the ALTERNATOR below

What’s a Mechanical To Electrical Energy Convertor?

Electrical OUT(rotor winding assembly, stator windings) …used to recharge car battery and operate electrical system

converted to

Thermal Energy OUT (friction between stationary and rotating rod) …used to fuse/weld metal components together

Rotational mechanical energy IN(rotating steel rod)

Mechanical Energy Convertors

• takes a mechanical energy input and converts it into useful thermal energy output• check out the SPIN WELDER below

What’s a Mechanical To Thermal Energy Convertor?

converted to

Stationary Steel Rod

Friction Welding occurs here

Rotating Steel rod

Thermal energy used to fuse components

Mechanical Energy Convertors

• no matter what type of energy convertor, they all have efficiency• efficiency is a measure of the extent of useful energy produced• calculated as a % of energy out versus energy in

Efficiency of an Energy Convertor

% Efficiency of Energy Convertor

Energy Output= X100%Energy Input

Remember: Energy is work so you could also have:

% Efficiency of Energy Convertor

Work Out= X100%Work In

HOW EFFICIENT ARE YOU?????

Mechanical Energy ConvertorsImportant Equations Related to Energy ConvertorsSince Energy is Work, here is a summary of work and energy equations:

Mechanical Work&Energy:

W=FxD

W=TxAngleFluid Work & Energy: W=∆px

VW=px ∆ V

Electrical Work & Energy:

W=∆Vxq

Thermal Work & Energy:

Ek=1/2mv 2 or 1/2Iω 2

H=mc∆T

E=Pxt

And of course, don’t forget the EFFICIENC Y equation!

Homework: Complete Student Exercises from pg.19 in workbook (copy questions and correct answer)

Mechanical Energy ConvertorsAnswers to Student Exercises

10. As a minimum, include the converters discussed in presentation (vane pump, spin welder, alternator)

1. Output energy

4. Less than

3. C. less than 100%

2. Divided

5. Same6. A, b, c, All

correct7. Mechanical8. B9. D