Specific fuel consumption
The specific fuel consumption is a measure of the efficiency of an internal combustion engine . It is defined as the ratio between fuel consumption per period and the mechanical power output. There is a comparable characteristic value for jet and rocket engines. It is described in the article Specific Impulse .
The specific fuel consumption is usually given in g / kWh .
Specific fuel consumption as a benchmark
Internal combustion engines can only be compared with one another on the basis of the specific fuel consumption if the power measurement is carried out according to the same standards and the fuels have the same calorific value per unit weight. The article horse power shows which different measurement methods are used to determine engine power.
Conversion into other units
In the Anglo-American system of measurement , the specific fuel consumption of internal combustion engines that deliver the power to a shaft is called Brake Specific Fuel Consumption (abbr .: BSFC) and is specified in lb / (hp · h). Older German-language literature also gives fuel consumption in grams per horsepower hour (g / PSh).
- Conversion table
lb / (hph) | g / kWh | g / PSh | |
---|---|---|---|
1 g / kWh = | 0.001644 | - | 0.73549875 |
1 lb / (hp * h) = | - | 608.277 | 447,387258 |
1 g / PSh = | 0.0022352 | 1.3596216 | - |
In Anglo-American, the decimal point is to be replaced by a decimal point.
Specific fuel consumption and efficiency
The efficiency of an internal combustion engine relates to the calorific value of the fuel and not to its (higher) calorific value . The calorific value is usually given in kJ / kg or kWh / kg. The conversion is: 1 kWh = 3600 kJ. If the specific fuel consumption (b e ) and calorific value (H U ) of the fuel are known, the efficiency (η) can be calculated as follows:
Example: A diesel engine has a specific fuel consumption (at a certain operating point) of 198 g / kWh. The calorific value of the diesel fuel used is around 11.9 kWh / kg. The efficiency is calculated as follows:
Fuel type | MJ / kg | kWh / kg |
---|---|---|
diesel | 42.9-43.1 | ≈ 11.9 |
Regular gasoline | 41.2-41.9 | ≈ 11.5 |
Premium gasoline | 41.2-41.6 | ≈ 11.4 |
Aviation Fuel ( AvGas ) | 43.5 | ≈ 12.1 |
Kerosene | 43 | ≈ 11.9 |
It should be noted that the usual fuels consist of fuel mixtures and the calorific values are therefore not constant. Examples are winter diesel, summer diesel and gasoline with different degrees of ethanol admixture.
Maps of specific fuel consumption
The specific fuel consumption - and thus the efficiency - is not a constant value, but depends on the operating state of the engine. Depending on its speed and load, different values result. However, often only a single value is given. If no further explanation follows, this value is the so-called “best value”, i.e. the achievable minimum.
A characteristic field of the specific fuel consumption, which is also referred to as a “shell diagram”, is much more meaningful . In addition to the “best point”, all other values at full load and at part load can also be read from this diagram.
These characteristic fields are of particular importance for the design and control of manual transmissions. By selecting the appropriate gear ratio, the engine speed and load condition can be set so that the respective minimum consumption is achieved.
Comparative values
engine | Type | Specific fuel consumption [g / kWh] |
fuel |
---|---|---|---|
Four-stroke engine | Truck / car | 180-210 | diesel |
Four-stroke engine | Car | 220-250 | petrol |
Rotary engine | Car / motorcycle | 300-380 | petrol |
Gas turbine | Cars / Aviation | 300-1000 | Kerosene |
Pulverized coal engine | Stationary engine | 340-350 | Coal dust |
Two-stroke engine | motorcycle | 380-500 | petrol |
Steam engine | steam train | 965-1260 | coal |
Selected engines / power units
Application example | Engine type | year | Power kW] | Working principle | Specific fuel consumption [g / kWh] |
fuel |
---|---|---|---|---|---|---|
1940s industrial engine | MAN D 0534 G | 1942 | 51.5 | diesel | 217.5 | Gas oil |
Industrial engine from the 1950s | Mercedes-Benz OM 636 | 1952 | 29 | diesel | 286 | Diesel fuel |
First diesel engine | - | 1897 | 13 | diesel | 324 | petrol |
Brush cutter ( four-stroke engine ) | Honda GX 35 | 2011 | 0.94 | Otto | 390 | petrol |
Chainsaw ( two-stroke engine ) | Stihl MS 391 | 2016 | 3.3 | Otto | 421 | petrol |
Wankel engine for drone | UAV Engines AR801 | 1999 | 30th | Wankel | 304 | petrol |
Industrial diesel engine 2000s | VW EA188 1.9 l | 2005 | 63 | diesel | 207 | Diesel fuel |
Passenger car diesel engine from the 2000s | BMW N47 | 2007 | 130 | diesel | 198 | Diesel fuel |
Passenger car gasoline engine 2010s | Ford EcoBoost | 2011 | 74 | Otto | 240 | petrol |
1960s industrial engine | ЯМЗ-238М2 | 1960s | 176 | diesel | 214 | Diesel fuel |
Industrial diesel engine from the 2010s | OM 936.972 | 2015 | 220 | diesel | 212 | Diesel fuel |
1930s aircraft engine | BMW 114 | 1936 | 460 | diesel | 266 | Gas oil |
1940s aircraft engine | Junkers Jumo 205 | 1940 | 647 | diesel | 211 | Gas oil |
Formula 1 engine 1980s | Honda 1.5L | 1987 | 559 | Otto | 258 | Premium gasoline |
Shaft turbine | Klimow TW3-117 WM | 1972 | 1.103 | Joules | 299 | Kerosene |
1940s aircraft engine | Pratt & Whitney R-4360 | 1945 | 2,610 | Otto | 265 | petrol |
Turboprop | Kuznetsov NK-12 | 1955 | 11,032 | Joules | 218.9 | Kerosene |
2-stroke marine diesel | MAN S80ME-C9 | 2014 | 27,060 | diesel | 164.4 | Heavy oil ISO 8217 |
2-stroke marine diesel | Wärtsilä RT-flex96C | 2008 | 84,420 | diesel | 171 | Heavy oil ISO 8217 |
4-stroke marine diesel | Wärtsilä 8V31 | 2015 | 4,480 | diesel | 170.6 | Heavy oil ISO 8217 |
2-stroke HPDF marine engine (diesel cycle, pilot ignition), slow speed, SCR cat |
MAN 6G70ME-C9.5-GI | 2021 (sim.) | 21,840 | diesel | 139.6 + 1.3 | LNG or LBM + heavy fuel oil ISO 8217 |
1960s boxer engine | VW type 126 | 1969 | 35 | Otto | 306 | petrol |
Rotary engine of the NSU Ro80 | KKM 612 | 1967 | 85 | Wankel | 313 | petrol |
Industrial engine from the 1890s | Hornsby Akroyd engine | 1891 | 5.6 | Akroyd | 460 | Gas oil |
Individual evidence
- ^ Bosch: Kraftfahrtechnisches Taschenbuch, 28th edition, May 2014. ISBN 978-3-658-03800-7 , p. 33.
- ↑ Klaus Schreiner: Basic knowledge of the internal combustion engine . 2nd Edition. Springer Fachmedien, Wiesbaden 2015, ISBN 978-3-658-06186-9 , 3.3 What does an indication of 200 g / (kWh) actually mean?
- ^ BOSCH (ed.): Kraftfahrtechnisches Taschenbuch . 28th edition. 2014, ISBN 978-3-658-03800-7 , p. 316 .
- ^ A b Bosch: Kraftfahrtechnisches Taschenbuch. 28th edition, May 2014. ISBN 978-3-658-03800-7 , p. 457.
- ^ A b Robert Bosch GmbH: Kraftfahrtechnisches Taschenbuch . 19th edition. 1984, ISBN 3-18-418005-0 , p. 329.
- ^ A b Bosch: Kraftfahrtechnisches Taschenbuch . Stuttgart, 10th edition 1950, p. 225.
- ^ Bosch: Kraftfahrtechnisches Taschenbuch. 26th edition, 2007. ISBN 978-3-8348-0138-8 , p. 509.
- ↑ Hans Kremser: The structure of high-speed internal combustion engines for motor vehicles and railcars. In: Hans List (Ed.): The internal combustion engine. Volume 11. Springer, Vienna 1942, ISBN 978-3-7091-5016-0 . P. 136
- ↑ Manual Mercedes-Benz OM 636, p. 45
- ↑ Günter Mau: Manual Diesel Engines in Power Plant and Ship Operation . Vieweg. Braunschweig / Wiesbaden. 1984. ISBN 978-3-528-14889-8 . P. 7
- ↑ breitband-lambda.de Studienarbeit T3100. Page 58 ff. (Performance information p. 67)
- ↑ dlg-test.de Stihl MS 391
- ↑ AR 801 50bhp
- ↑ TDI-Industriemotor, p. 3. ( Memento from March 12, 2017 in the Internet Archive )
- ↑ auto-innovations.com
- ↑ Ernst, R.; Friedfeldt, R.; Lamb, S.; Lloyd-Thomas, D.; Phlips, P.; Russell, R.; Zenner, T: The New 3 Cylinder 1.0L Gasoline Direct Injection Turbo Engine from Ford . In: 20th Aachen Colloquium Automobile and Engine Technology . Aachen 2011.
- ↑ Силовой Агрегат ЯМЗ-238М2. (Russian), accessed September 24, 2017
- ↑ dlg-test.de Unimog U 530
- ↑ Michael Trzesniowski: racing car technology . 2nd Edition. Vieweg + Teubner, Wiesbaden 2010, ISBN 978-3-8348-0857-8 , p. 529
- ↑ Technical data TW3-117
- ^ Gerard L. Blake: Operating the Pratt & Whitney R-4360-59B. (No longer available online.) Archived from the original on November 5, 2016 ; accessed on November 6, 2016 .
- ↑ НК-12МП - Основные характеристики двигателя ( Memento from April 25, 2017 in the Internet Archive )
- ↑ MAN B&W S80ME C9, p. 50.
- ↑ WÄRTSILÄ RT ‑ flex96C AND WÄRTSILÄ RTA96C TECHNOLOGY REVIEW
- ^ Wärtsilä-31 engine
- ↑ SEA / LNG (Ed.): LNG as a marine fuel - The investment opportunity. In: Selbstverlag, February 24, 2020, (English). sea-lng.org , PDF, 2,450 kB, accessed on February 29, 2020.
- ^ VDA: Volkswagenwerk AG Wolfsburg - Type VW double cabin. Group 13, number 223b. Frankfurt am Main December 1969.
- ^ Matthias Parschau: Properties of Wankel Engines , accessed on April 1, 2020
- ^ Friedrich Sass: History of the German internal combustion engine construction from 1860 to 1918 , Springer, Berlin / Heidelberg 1962, ISBN 978-3-662-11843-6 . P. 418