System of Units: US Customary & Metric/SI Units

• Contents are subject to IP Laws
• Materials in the lecture module should only be used for the purpose of the course, and should not be distributed or reproduced without consent
• copyrighted materials are included under the context of fair use

System of units

• System of units describes measuring components in either US Customary Units or Metric/SI Units
• Distance is measured in feet (ft) or meters (m)
• Displacement measures movement from one place to another
• Length refers to the physical size of an object
• Area is measured in square feet (ft²) or square meters (m²); it describes the number of unit squares within a surface
• Temperature is measured in Fahrenheit (°F), Celsius (°C), Kelvin (K)
• Temperature refers to the degree of hotness or coldness of an object
• Volume is measured in cubic feet (ft³) or cubic meters (m³); it describes the amount of space occupied by a three-dimensional figure
• Weight is measured in pounds (lb) or Newtons (N); is the force of gravity acting on a body
• Force (lbf; N) describes an action causing motion or a change in the motion of an object; it has direction, magnitude, and a point of application
• Pressure is measured in pounds per square inch (psi), Newtons per square meter (N/m²), or Pascals (Pa), pressure is described as the amount of force or thrust exerted over a given area
• Time is measured in seconds, minutes, or hours; it describes a measure of duration
• Velocity or Speed is measured in feet per minute (ft/min), or meters per second (m/s); is the measure of movement over time
• Power is measured in pound-feet per second (lb-ft/sec), Newton-meters per second (N-m/s), or watts.
• Power the the rate of doing work: Work (W) is the result of a force acting through a distance.

$$Power = \frac{Work}{Time} = \frac{Force \cdot distance}{Time}$$

• Torque is measured in pound-feet (lb-ft) or Newton-meters (N-m); is the application of force through a lever arm resulting in a twisting or rotary movement

$$Torque = Force \cdot arm \ length$$

• Horsepower (hp) is commonly used to indicate the work output of humans, draft animals, and mechanical prime movers measured as 33,000 lb-ft/min or 746 watts.
• The industrial standard in Japan is use metric horsepower

$1 , hp = 746 , watts = 33,000 , lb-ft/min$

Common terms in agricultural and biosystems engineering (ABE)

• Tool
• Machine
• Agriculture
• Agricultural machinery
• Agricultural equipment
• Mechanize

Agricultural Mechanization

• Agricultural mechanization is the utilization of any machine to accomplish a task or operation associated with agricultural production
• Agricultural mechanization employs the use of human, animal, and mechanical power

Scope of Agricultural Mechanization

• Utilization
• Manufacture
• Distribution
• Provision of after-sales services of tools, implements, and machines

Objectives of Mechanization

• Reduce drudgery in farm work
• Increase productivity of farm workers
• Increase the timeliness and quality of farm work

Levels of Agricultural Mechanization

• Hand tool technology means that a person can cultivate approximately 1 hectare of land
• Animal Draught Technology means that a carabao can make a maximum sustained pull at 10% of its weight for about 2-3 hours per day at a normal speed of 0.6-0.8 m/sec
• Mechanical Power Technology

Power Sources in Agriculture (Developing Countries)

• 70% human power
• 20% animal power
• 10% engine power

Farming and Drudgery

• Farming is hard work often involving drudgery
• Farm workers seek to reduce drudgery
• Progress is being made using power-operated machines

Farm Power Development

• The more farm operations become mechanized, the less drudgery is required and the less workers needed
• High mechanical efficiency results in high precision, increased production, lowered unit costs, and increased profits

Profit and Machinery

• Power machinery can increase profit by:
  • Increasing total production
  • Reducing costs
  • Improving product quality

Utilization of Farm Power

• Tractive power pulls equipment
• Rotative power drives attached or drawn equipment
• Automotive power hauls

Factors in selecting size and type of power:

• Kind and size of farm
• Work to be done
• Seasonal Demand
• Field and Operating Condition

Consequenses of Improper Selection of Power:

• Overpowering
  • High overhead charges
  • Damage to the machine
• Underpowering
  • Overloading the power unit
  • Excessive repair
  • Annoying shutdowns
  • Slow operation
  • Unsatisfactory work

Sources of Power on the Farm

• Human labor
• Draft animals
• Solar
• Biomass
• Wind
• Flowing water
• Heat engines
• Electric motors

Human and Animal Power

• Primary sources of power in the farm

A Glimpse of History about Animal and Human Power

• Man used muscles to walk long distances, hunt animals, and till the soil
• Man learned to tame animals he hunted for food, providing pulling power
• Man learned the use of sleds for transporting cargoes, use of rollers underneath the sleds, and finally the use of wheels

Greatest Inventions of Man:

• Fire - discovery
• Wheel - invention

Power in the Farm

• Human and animal power is still a major source of power in the farm because of:
  • Size of the farm
  • Topography
  • Crops grown
  • High cost of equipment
  • High cost and no availability of fuel
  • Availability of low cost labor

Human Power

• Consumes energy at a sustainable rate of only about 250 W (0.0335 hp)
• About 25% conversion for light work and 5% conversion for heavy work
• Naturally, higher rates can be maintained for shorter periods
• Adopts a working mode that incorporates appropriate rest period
• Makes instantaneous decisions on force exerted to accomplish task and conserve energy
• Chooses the appropriate tools for a given production unit operation
• Changes from one task to another readily and rationally, exhibiting a versatility that no other power source is capable of
• Man is best suited to farm operations that require judgment rather than just manual labor

Animal Power Advantages Over Mechanical Power:

• Animals can be grouped into different size units
• Have high temporary overload capacity
• Uses fuel produced in the farm
• return fertilizer to the soil

Animal Power Disadvantages

• Cannot work continuously
• Subject to weather conditions
• Maybe temperamental
• May become unwieldy in large teams
• Not suited for stationary work

The Philippine Carabao

• In the Philippines, the carabao is the major beast of burden.
• Can generate 1 hp walking continuously under favorable conditions.
• Carabaos are confined mostly to pulling operations such as plowing, harrowing, cultivating, and transport
• There are about 3.075M carabaos in the Philippines (BAS, Jan 2011) and about 70% to 75% is used for draft work.
• Contribution of animal power in the farm is about 0.225 hp/ha.

Carabao (ISLAW):

• Has low initial cost and is easy to maintain
• Rarely bogs down in mud
• Can work closer to the levees
• Is mobile in most terrain conditions
• If female, is capable of reproduction
• Source of milk, meat, leather, and fertilizer

Carabao Limitations

• Low work output
• Prone to disability by disease, poisoning, lost by rustling and death
• Requires daily attention, such as feeding and pasturing
• Under poor management practices, causes unsanitary conditions

Kalabaw Power

• Can make a maximum sustained pull of 10-15% of its weight for about 2 - 3 hours per day at a normal speed of 0.6 - 0.8 m/sec
• Can develop an output of 0.7-1.3 horsepower

$500 , kg , Carabao \rightarrow 75 , kg , draft , at , 0.7 , m/s \rightarrow 515 , W , (\sim 0.7 , hp)$ $\frac{500kg}{75kg}\cdot \frac{0.7m/s}{}= 4.667m/s$

Maximizing Animal Potential

• Consider environmental factors that define the working condition, choice of animals (breed, species, sex, temperament), harnessing system, etc
• Livestock management (feeding, training, care, watering)

Solar Energy

• Solar energy used for crop and grain drying as well as solar thermal conversion and photovoltaic means
• Water wheel utilizes flowing/falling water streams:

Water Wheel Power

• Power developed in two factors:
  • Volume of water flowing per unit time
  • Head or vertical distance of water drops at a point where power Installation is located

Wind Mill

• Used for pumping water and running small electric generating plants
• Limited for farm use (cannot be controlled and seldom available when needed)
• Used generally for water pumping
• The maximum energy or power recovered from the wind (kinetic energy of motion) = 59.3%

Internal Combustion Engine

• A highly efficient device for converting heat energy of fuel into mechanical energy

Electrical Motor

• Device used to convert electrical energy into mechanical energy
• More efficient than ICEs

Efficiency of Various Electric Motors

• Electric motors: between 50 to 90 %
• Gasoline engine: between 25% to 30%
• Diesel engine: between 30% to 36%

Electric Motors

• Simple and compact in construction
• Light in weight per hp
• Requires little attention and limited care and servicing
• Produce a smooth, uniform power
• Adaptable to uniform or variable loads
• An engine is a mechanical device used to convert the heat energy of fuel, produced as a result of combustion, into mechanical energy

Types of Engines

• There are two types of egines: External and internal

External Combustion Engine

• Also known as steam engine
• Fuel is ignited and burned outside the cylinder
• Heat energy is applied indirectly to the piston by an intermediate medium (water vapor)
• Steam is generated in a boiler which is entirely separate from the engine cylinder

Internal Combustion Engine

• Fuel is ignited and burned inside the cylinder Ignition of compressed mixture causes rapid combustion
• Instantaneous application of pressure applied to the piston
• Piston is consequently set in motion and power is generated

Advantages of ICE over ECE

• More efficient
• Weighs less per hp
• More compact
• Original cost less per hp
• Less time and work necessary preliminary to starting
• Less time and attention required while in operation
• Greater range of adaptability

History of Internal Combustion Engines

• 1860: J.J.E. Lenoir developed the first fairly practical engine; mechanical efficiency was up to 5%
• 1867: Otto-Langen engine, efficiency improved to about 11%,
• 1876: Nicolaus Otto developed his four-stroke prototype engine
• 1878: Clark Dugald developed the first two-stroke cycle engine
• 1884: Alphonse Beau de Rochas described the principles of the first four-stroke cycle
• 1892: Rudolph Diesel perfected his compression ignition engine
• 1920: Compressed engines were small enough to be used with car and trucks

Beau de Rochas Principles

• Conditions for ICE to achieve maximum efficiency: The largest possible cylinder volume with the minimum boundary surface The largest possible working speed The greatest possible expansion ratio
• The greatest possible pressure at the beginning of expansion

Physical Nomenclature

• Bore (d ) – diameter of the engine cylinder
• Stroke (L) – distance the piston travels from bottom-dead center (BDC) to top-dead center (TDC)
• Crank throw - the distance from the center of the crankshaft to the center of the crankpin
• Clearance volume (Cv ) – volume within the cylinder above the piston when the piston is at the top of its stroke
• Piston displacement (Pd) – the volume displaced by the piston during one stroke; swept volume

$$P_d = \frac{\pi d^2}{4} \cdot L$$

• Engine displacement (Total Pd) – sum of the Pd of individual cylinders; N is number of cylinders

$$Total P_d = N \cdot P_d$$

• Total cylinder volume (V) – the sum of the piston displacement and clearance volume

$$V = P_d + C_v$$

• Compression ratio (Cr) – ratio of total cylinder volume to clearance volume

$$C_r = \frac{P_d + C_v}{C_v}$$

Major Components of ICE

• Air filter
• Intake valve
• Exhaust valve
• Spark plug
• Piston
• Connecting rod
• Crank pin
• Crank shaft
• Carburetor

Engine Components

• CLASSIFIED INTO FOUR (4) GROUPS: Power chain – to receive, exert, and transmit the motive forces Stationary parts – to constrain and support moving parts Valve system – time the operating sequence Auxiliary parts & Accessories – to cool and lubricate the surfaces and provide ignition and fuel for the engine

• Power Chain*

• Piston receives and transmits pressure forces to chamber

• Piston ring reduce #contact

• Connecting rod transmits piston to the crankshaft

• Stationary parts*

• Cylinder Block confine the space for the expanding gases and forming a combustion chamber

• Cylinder head - Houses the valves.

• Combustion chamber - Is The end of the cylinder between head and Piston face.

• Crankcase- supports the shaft.

• Valve System components*

• Valves open and closing parts, chambers

• Valve Stem guide fits tightly to the cylinder to guide the valve

• value letter lower the valves

• Auxiliary System*

• Spark plug electrical device to combustion

• Fuel injector nozzle that sprays fuel.

• Catalytic Converter reduce emissions

Theory of Operation

• The function of all internal combustion engines is to convert fuel (chemical energy) to power.
• This is accomplished by burning a fuel in a closed chamber and using the increase in temperature within the closed chamber to cause a rise in pressure which produces a force on the head of the piston causing it to move.
• The linear movement of the piston is converted to rotary motion (at the crankshaft).
• Rotary motion is more useful than linear movement

Eight (8) Requirements for Operation

• Air (oxygen) must be drawn into the engine cylinder as well as fuel
• The air and the fuel must be mixed - Compressed
• Fuel Mixture is ignited by the spark plug
• Increase is rapid
• 8TH expelled from the engine.

Engine Classification

• Type of ignition is spark Ignition (SI)/ Compression Ignition (CI)
• A 4- Stroke Cycle / 2 stroke Cycle
• Valve location*
• Valves in head.
• Valves in block.

Engine Classifications based on position and number of cylinder

• Single Cylinder
• V engine
• W engine
• Reciprocating Engine
• Gas, diesel
• Dual fuel
• LPG fuel

2 air intake process:

• Super charged
• Turbo charged: Fuel in put

Type of cooling

• Air cooled
• Water cooler

LECTURE # 4 BASIC THERMODYNAMICS OF ENGINES

• Thermodynamics:*
• Physical science that deals with conversion of energy

1st Law

• thermodynamics* energy can neither be created or destroyed.

$$PV_1= PV_2 =c$$

Charles Law

Volume is kept consistent. Pressure also kept consistent absolute temperature.

$$P=MRT$$

Example Of given:

absolute temp absolute Barometric all has air volume.

• formula* Density = weight over velocity, = air divided by R constant

Two pressure change, polytropic

$$TP=\pi _n$$

$$V_2 = \frac{V_1}{2+ \frac 1{16}}$$

Two Way of combustion

• Rapid Explosion
• Really is slowly.

Assumption

Adiabatic processes means constant temperature. Specific heated processes has remained constant but cycle.

Cycle Operation:

• Power
• Exhaust
• Compressions
• Intake

STROKE cycle PRINCIPLE

begins with a piston moment

• Field with air are few make sure
• At the completion, the push up and both are close
• STROKE PRINCIPLE*

Power stoke spark of plug result in action

At or near the spark plug will light

• Compression stroke cylinder fill with the fuel mix
• Moves up compressed

Advantage of Stroke

• Eliminates shaft. Mix with you always to. Operate in the position.

Comparison of Strokes

• full is low
• Noiset

Timing.

Engine fuel the preaction. Start ignition before top dead conters

• Bob (B=4 is full stroke*

• Average* fuel mix

• What does all the do. Order of cylinder what the are. Firing by delivery of fuel.

30. Type of Engine

• Stroke 2 Eliminating came shaft the valve. Has no sump holding is even.

First Law of Thermodynamics

• Energy Conservation: Energy cannot be created nor destroyed, although it can change forms or flow from one place to another
• The total energy of an isolated system remains the same

Second Law of Thermodynamics

• Processes only occur in a certain direction, “Heat will, of itself pass from a hot to a cold substance, but external work is required to transfer heat from a cold substance to a hot substance

Boyle's Law

• Temperature is kept constant

$$P_1 \times V_1 = P_2 \times V_2 = c$$

• Where P and V represents volume

Ideal Gas Law

$$PV = MRT$$

• P represents pressure
• V represents volume
• M equals the quantity of gas
• R=Specific gas constant, absolute temperature
• T equals the absolute temperature

Air formula calculation of one density

• where row represents air density

Formula's for Heat energy flow

specific heat = is required to rise temp.

Polytropic process to find pressure

• Pressure = value, times the second volume

Polytopic process to find Temperature

• The heat of gas and the formula
• A two and always effect.

Two engine combustion parts

• First rapid to ignition
• Second slow the few injection
• To heat the high compress