C01-AENGR1105-Sources of Power-PPT (2).pdf

CENTRAL LUZON STATE UNIVERSITY College of Engineering Department of Agricultural and Biosystems Engineering AENGR 1105: BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT CO1: SOURCES OF POWER IN AGRICULTURE MAY ALISBO CABRAL, M.Sc....

CENTRAL LUZON STATE UNIVERSITY College of Engineering Department of Agricultural and Biosystems Engineering AENGR 1105: BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT CO1: SOURCES OF POWER IN AGRICULTURE MAY ALISBO CABRAL, M.Sc. Instructor  LEARNING OUTCOME Discuss the relevance of power in agriculture in the local and international scenes, and Explain the different sources and requirements of power in agriculture. Solve problems related to power measurement using different sources Copyright: Borrowed materials included in this lecture are owned by their respective copyright holders. The university and author/s do not claim ownership over them. AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  INTRODUCTION Farm power - one of the most expensive and critical inputs when growing a crop. Power sources in agriculture production: ✓ Humans ✓Animals ✓machines, and ✓renewable energies. When undertaking different operations on a farm, a certain amount of work is required to complete the task. Power or the rate of doing work can be expressed as horsepower or Kilowatt. AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  A farm power for various agricultural operations can be broadly classified as A. Tractive work Requires pulling or drawing efforts or high traction or torque usually supplied by tractors Example of agricultural operations: Plowing or land preparation Planting and seeding Crop Cultivation Harvesting Transportation AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  B. Stationary work usually accomplished utilizing a belt, gears, or direct drives Example of agricultural operations: Silage cutting Feed grinding Threshing Winnowing Lifting of irrigation water AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  Agricultural Power Sources 1. Human 2. Animal 3. Renewable (solar energy, Biogas, biomass, water and wind energy) 4. Electrical 5. Mechanical (oils, engines and tractors) AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  1. Human Power Main source of power for operating small tools and implements Also employed for doing stationary work like threshing, winnowing, chaff cutting and lifting irrigation water Land preparation (plowing, soil leveling, constructing bunds and drains) Plant establishment (seeding and planting) Pests control Crops harvesting and transporting Grain processing AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  Advantage Disadvantage Costliest power compared Easily available to all other forms of Used for all types of power, work Very low efficiency, cannot compete with animals or Intelligence other source of energy (decision making Requires full maintenance and manual when not in use, affected dexterity) by weather conditions and seasons Not suitable as power source for repetitive task AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  Human Power Measurement Table 1. Man-days per hectare of selected agricultural operation Operation Average Human Work Rate (Man-days/ha) Land Clearing 32.6 Ridging for Cassava 43.8 Mound Making for Yam 57.8 Cassava Planting 28.3 Yam Planting 28.3 Weeding Root Crops 36.7 Weeding, general 40.0 Cassava Harvesting 28.5 Yam Harvesting 32.0 AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  Human Power Measurement Table 2. Man-Hour Requirement per Hectare of Various Agricultural Operations Operation Persons-hr/ha Tillage with hoe 100-300 Water buffalo plowing flooded soil 30 – 60 Water buffalo comb harrowing 40 – 60 5-hp power tiller plowing wet soil 20 –40 10-hp hydro tiller 4.4 Broadcasting 3.3 Hand weeding transplanted rice 120 - 320 Harvesting rice with sickle 60 –80 5-hp IRRI axial-flow thresher, 4 men feeding 350 – 700 kg/hr AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  Human Power Measurement Power generated Number of Persons Needed 𝐏𝐠 = 𝟎. 𝟑𝟓 − 𝟎. 𝟎𝟗𝟐 𝐥𝐨𝐠 𝐭 Where: Pg = power generated ,hp 𝐌𝐡 × 𝐀 𝐌= 𝐓 t = time , minutes Area Covered Time to Finish Work 𝐌𝐡 𝐌 𝐀= 𝐓= 𝐌×𝐓 𝐌𝐡 × 𝐀 Where: T = time, hr M = number of person, man 𝑀𝑎𝑛−ℎ𝑟 Mh = man-hour requirement per hectare, , 𝐻𝑎 A = area, ha AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  Human Power Measurement Sample Problem. Ten hectares farm is to be planted with rice by broadcasting. The owner of the farm wishes that his farm could be finished within one day (8 hrs per day). How many people would be required to do the job? Given: Area of the farm = 10 hectares Operating Time = one day @ 8 hours Required: No. of persons to employ Solution: 𝐡𝐫 𝟑. 𝟑 𝐌 − × 𝟏𝟎𝐡𝐚 𝐌= 𝐡𝐚 𝟖 𝐡𝐫𝐬 = 4.125 or 5 Person AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  2. ANIMAL POWER widely used as the major power source in many countries. Oxen and caribou or buffalo are the most popular animal power source for agricultural practices, although horses, donkeys, mules, and camels are used in many countries for transportation. It is one of the oldest sources of farm power used in land preparation, weed management, crop threshing, and transport. Generally, a medium-size bullock can develop between 0.50 to 0.75 hp. AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  2. ANIMAL POWER Oxen or bullock - Generally a medium size Mule – Offspring of a male donkey and a bullock can develop between 0.50 to 0.75 female horse hp. Small size bullocks are not able to develop even 0.50 hp and most of them are not fit for heavy work. AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  2. ANIMAL POWER In most areas, domestic animals are still the principal source of farm power because of the following reasons: Adaptable to small farm sizes and rolling topography Crops not suited for mechanization makes use of animal power Lack of suitable fuel at reasonable cost High initial cost of mechanical equipment Plentiful supply of low-cost labor AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  Advantages Cheap to maintain Multi-purpose use for meat and milk, Easily available, great reserve for emergencies and temporary loads Used for all types of work; flexible in size of power unit Low initial investment, Practically adaptable to all draft work; fairly good traction in wet and loose ground Can be produced in the farm Supplies manure to the field AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  Disadvantages Animals have limited daily working hours since it requires resting hours Requires a relatively large amount of time for feeding, harnessing, care and protection against pests and disease Limited range of working conditions; work at heavy load limited to short time Required feed and care when not working Relatively and low working speed Cannot work efficiently in hot weather and not efficient for stationary work Animals require training AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  Determination of Animal Power Since the horse was the chief source of power during the early times, it became the ready reference when computing for power. The horse working continuously for several hours and walking at 2.5 mph should not pull more than 1/10 to 1/8 of its body weight. The horse can travel up to 20 miles/per day without undue fatigue. 1000 lb horse can develop.67 to.83 hp 1,200 lb horse can develop.8 to 1 hp 1,600 lb horse can develop 1.07 to 1.33hp The power range of farm animals = 0.7 to 1.3 hp Power = force * speed AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  Determination of Animal Power A well-trained horse can exert an overload of over 100% for a short time. For few seconds and over a limited distance of perhaps 30 ft (9m) or less, a horse can exert a maximum pull of 60 to 100% of its actual weight. Under such conditions, a horse may develop as much as 10hp depending upon its size and pulling ability. AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  Draft horsepower 𝐅×𝐕 𝐃𝐇𝐏 = (𝟕𝟔. 𝟐 𝒌𝒈 − 𝒎Τ𝒔)/𝒉𝒑 Where: DHP = draft horsepower, hp F = draft, kg V = velocity of travel, m/s AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT Draft horsepower Sample problem. Compute the draft power develop by a 800 kg buffalo pulling 80 kg load on a plow and traveling at a speed of 0.9 m/sec. Given: weight of animal= 800 kg draft = 80 kg speed =0.9 m/sec Required: Draft horsepower Solution: DHP = F x V = 80 kg x 0.9 m/s = 72 kg-m/sec or 0.95 hp AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  Table 3. Draft and horsepower generated by selected draft animals Average Power Approximate Average Animal Weight Developed Pull (kg) Speed (m/s) (kg) (Hp) Light Horse 400-700 60-80 1.0 1.00 Bullocks 500-900 60-80 0.60-0.85 0.75 Bufallos 400-900 50-80 0.80-0.90 0.75 Cows 400-600 50-60 0.70 0.45 Mules 350-500 50-60 0.90-1.00 0.70 Donkey 200-300 30-40 0.70 0.35 AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  Draft and horsepower generated by animals Draft animals can be harnessed singly or in multiple numbers to match the pulling capacity or load. Generally, pulling efficiency decreases with the number of animals harnessed together. Horses are harnessed in several numbers while oxen are mostly harnessed in pairs. A poorly designed or ill-fitting harness reduces the power available from the animals and make it suffer physically AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT Draft and horsepower generated by animals Table 4. Harnessing factor of one or more draft animals No. of Factor Animals Animal draft/power can be computed by : 1 1.0 2 1.9 Draft = Specific draft x factor 3 2.5 4 3.1 5 3.5 6 3.8 AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT Draft and horsepower generated by animals Sample Problem. Six (6) horses can provide a pulling load of 60 kg per animal. How much draft can the 6 horses provide in pulling a load? Given: No. of Animals = 6 Specific draft = 60 kg/animal Required: Total draft of the animals Solution: Draft = 60 kg/horse x 3.8 = 228 kg AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  3. RENEWABLE POWER 1.Water 3.Solar 2. Wind 4.Biomass AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  3. RENEWABLE POWER mainly obtained from renewable energy sources like sun, wind, biomass, etc. can be used for lighting, cooking, water heating, space heating, water distillation, food processing, water pumping, and electric generation. clean energy resource and inexhaustible. new renewables are also growing rapidly, including the small hydro, modern biomass, geothermal, and biofuels. play a key role in creating a clean, reliable energy future. using renewables to replace conventional fossil fuels can prevent pollutants into the atmosphere and help combat global warming AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  3.1 WATER POWER It can be generated from water located in a high elevation; Its potential energy can be directly converted into mechanical energy by utilizing special motors called turbines or water wheels. The action of the water will rotate the water wheels. This mechanical power, in turn, can be utilized to propel a wheel or can be converted into alternating current or electrical energy. Water power is utilized solely for stationary works and electric generation AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  Types of water masses movement to generate power Falling/flowing of streams of water through force of gravity Rise and fall of tides through lunar (and solar) gravity AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  Determination of Water Power Theoretical power available from falling water can be expressed as: 𝑃𝑡ℎ = 𝜌𝑞𝑔ℎ Where Pth = power theoretically available (W) ρ = density (kg/m3) (~ 1000 kg/m3 for water) q = water flow (m3/s) g = acceleration of gravity (9.81 m/s2) h = falling height, head (m) The actual power is about 60-80% less than the theoretical power (due to the hydraulic losses in conduits and turbines, mechanical losses in bearings and power transmission systems, and electrical losses in generators, station use, and transmission (for hydroelectric)). AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  Determination of Water Power Practically/actual available power can be determined following the equation below: 𝑃𝑎ℎ = 𝜌𝑞𝑔ℎ ∗ 𝑒𝑓𝑓 𝑃𝑎ℎ = 𝑃𝑡ℎ ∗ 𝑒𝑓𝑓 AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  Determination of Water Power Sample Problem. One cubic meter per second of water is falling at a head of 10 meters. What is the theoretical power available? Assuming that the efficiency of turbine is 80 %, determine the actual power available. Given: Discharge = 1m3/s Head = 10 meters Turbine efficiency= 80 % Required: Theoretical and Actual Power AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  Determination of Water Power Solution: 𝑃𝑡ℎ = 𝜌𝑞𝑔ℎ 𝑃𝑡ℎ = (1000 𝑘𝑔Τ𝑚3 ) 1 𝑚3 Τ𝑠 ( 9.81 𝑚Τ𝑠 2 )(10𝑚) 𝑷𝒕𝒉 = 𝟗𝟖, 𝟏𝟎𝟎 𝒘𝒂𝒕𝒕𝒔 𝒐𝒓 𝟗𝟖. 𝟏𝑲𝑾 𝑷𝒂𝒉 = 𝑃𝑡ℎ ∗ 𝑒𝑓𝑓 𝑷𝒂𝒉 = 𝟗𝟖, 𝟏𝟎𝟎 𝒘𝒂𝒕𝒕𝒔 ∗ (. 𝟖𝟎) 𝑷𝒂𝒉 = 𝟕𝟖, 𝟒𝟖𝟎 𝒘𝒂𝒕𝒕𝒔 𝒐𝒓 𝟕𝟖. 𝟒𝟖𝑲𝑾 AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  Water Power Generating Devices Hydraulic rotating prime movers ✓Water wheels (overshot, undershot, breast) ✓Tub wheels or flutter wheels Water wheels Water turbines ✓Turbines Hydraulic Rams Hydraulic Air Compressors AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  3.2. WIND POWER Wind also possesses power that can be harnessed using windmills. Energy is tapped by allowing windmills to rotate on an axis through the power of the wind. The rotating wheel, in turn, creates torque that rotates a shaft that produces mechanical power. However, this power source is less limited for farm use, cannot be controlled, and seldom available when needed. It is confined largely to water pumping or milling grains and electric generation AENGR1105- BASIC FARM MACHINERIES, MECHANIZATION AND WATER MANAGEMENT  Classification of Windmills 1. According to shaft orientation – vertical or horizontal. 2. According to blade material – sail, metal, wooden. 3. According to shaft speed – high speed (2 to 4 blades);