BIODIESEL. Lesson 4d Test biodiesel in a diesel generator. Developed by Engineering and Technology Curriculum Team

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1 BIODIESEL Lesson 4d Test biodiesel in a diesel generator

2 In a laboratory setting, test biodiesel in a diesel generator by estimating Btu. define energy density, kwh, and Btu calculate energy density, kwh and Btu convert values between the units of kwh and Btu

3 Fire Safety Always follow directions. Know where to locate and how to use the closest fire extinguisher. Do not use water to extinguish a fire involving biodiesel. Biodiesel is lighter than water, will float on the water, and spread the fire. Remember STOP, DROP, and ROLL! Know evacuation plan in case of fire.

4 The Big Picture Objective: measure how much energy biodiesel has compared to a standard value of diesel fuel. Method: run a diesel generator and measure the fuel consumed and run-time while generating an electrical output in kilo-watts (kw), and convert to Btu per volume of fuel.

5 Steps Step 1 Run generator on biodiesel while producing 2kW of power. Step 2 Measure fuel consumption and time. Step 3 Calculate volumetric energy density. Step 4 Convert from metric to standard Step 5 Estimate the energy in biodiesel fuel Step 6 Estimate the energy ratio of biodiesel fuel to diesel fuel.

6 Energy Conversions Fuel contains energy in the form of chemical bonds. A diesel engine changes chemical energy into mechanical energy (movement). A generator changes mechanical energy into electrical energy (electricity).

7 Diesel Generator A diesel generator is composed of a diesel engine and a generator. Engine Generator

8 Diesel Generator The modified diesel engine has two fuel tanks, one for diesel fuel and one for biodiesel. Diesel Container Biodiesel Container

9 Diesel Generator Each fuel tank uses a the same return line but a separate return container. Diesel Fuel Return Container Biodiesel Fuel Return Container

10 Diesel Generator The generator is connected to an electrical load. We use heaters. These heaters should be a known load. Ours are 2 KW together.

11 Kilo-Watt Power and Energy are different The kilo-watt is the SI unit of electrical power Electrical power = Voltage x Amperage The kilo-watt Hour is a unit of electrical energy. Since power is energy transferred per unit of time, 1 kwh = 1 kw x 1 h

12 Kilo-Watt A generator produced 2 kw of power for 3 min. How much energy was produced in kwh? 1h 2 kw 3min = 0. 1kWh 60min

13 Step 2 Measure Fuel Consumption Fuel consumption = fuel used. Two methods will be used: Measuring the amount of fuel used in a specified amount of time. (Class Demonstration) Measuring the time it takes to run a certain amount of fuel. (Performance evaluation)

14 Assumption about fuel consumption An assumption is made that the diesel generator that is being used is governed, meaning that it will produce the correct amount of electrical power despite the difference in fuel quality. This is accomplished by the engine burning more fuel when the fuel is less efficient in order to keep the RPM constant.

15 Step 3 Calculating volumetric energy density Volumetric energy density is the amount of energy per unit volume ρ vol = energy volume

16 Calculating volumetric energy density A generator produced 0.1 kwh of energy and burned 50 ml to produce that energy. What is that fuel s measured volumetric energy density? ρ vol = 0.1kWh = mL 3 kwh ml

17 A Btu Since we live in the U.S.A., we use Standard units. A Btu is a British thermal unit It is defined as the energy needed to raise 1 pound (lb) of water by 1ºF. We can use a direct conversion: 1 Btu = kwh

18 Unit Conversions For conversions, a ratio is needed kwh = 1Btu Make a fraction with the ratio, with the unit desired on top and the current unit on bottom x10 1Btu 4 kwh

19 Unit Conversions Multiply the current value by the fraction. The units should cancel x10 kwh 12,000Btu * = 3. 52kWh 1Btu The same procedure can be used to convert between any two units, as long as there is an equation that relates the two. 4

20 Step 4 Convert from metric values to standard values To convert our metric volumetric energy density into a volumetric energy density using standard units, we need to make two conversions: 1 convert kwh to Btu ( kwh = 1Btu) 2 convert ml to gal (3790 ml = 1 gal) Using the following formula, we can make both the conversions in the same equation. 1Btu x10 kwh 1gal = gal 1Btu 3790mL kwh ml

21 Simplify the conversion The conversion ration for converting between Btu/gal and kwh/ml is shown below. To make a conversion we simply follow the steps that were previously outlined for unit conversions. 1Btu = gal kwh ml

22 Energy density in Btu/gal How many Btu/gal is 2x10-3 kwh/ml? kwh ml 1 Btu gal kwh ml = 25,940 Btu gal

23 Why an estimate? Energy transferred Several factors affect our measurement. Heat transfer Friction (loss of energy in the form of heat) Air intake of engine (atmospheric pressure) Surrounding temperature (affects heat transfer) In order to be consistent, as many of these factors should be kept constant as possible.

24 Energy density of petrodiesel We can estimate the total value of Btu in biodiesel by making an estimate of how much energy we lose to the environment. Petrodiesel typically contains 128,700 Btu per US gallon. If petrodiesel is burned in the engine and 29,612 Btu per gallon of electrical energy is produced, then 23% (29,612/128,700) of the energy is used to produce electricity and 77% of the energy is lost to the atmosphere. We will call the 77% our %loss.

25 Assume similar loss If we assume that the same percentage of energy will be lost to the environment when we run the engine with biodiesel, we can make an estimate of how much energy is in biodiesel. We start with two equations: E total = E % loss = ele E E + loss total E loss

26 Calculate estimate Using algebra, we come up with the equation E total = E ele 1 % loss The total energy is equal to the electrical energy produced (0.167 kwh) divided by the percent transferred or one minus the percent lost to the environment (i.e. 23% = 0.23).

27 Step 5 Estimate the energy in biodiesel fuel Using the previous equation, plug in the numbers to find an estimate of the energy density of biodiesel. Btu 25,940 gal E = = 113, 000 total Btu gal

28 Step 6 Estimate the energy ratio of biodiesel fuel to diesel fuel To find the energy ratio of our fuel to diesel fuel we divide the energy estimate by the value for diesel fuel. 113, % 128, % This appears to be a good estimate since the average energy value of biodiesel is about 91% the average energy value of diesel fuel per volume. =

29 Better methods This method is not very consistent and yields poor values when compared to other methods. However, this method of testing is inexpensive and easy to accomplish. To get accurate values, we would use equipment such as a bomb calorimeter (to measure energy density).

30 Conclusion Now it is time for a demonstration! Use Class Demonstration 4d Diesel Fuel. Burn biodiesel, not a tree!