Performance diesel generators , diesel engines often use some of the major technical indicators to judge and measure . These specifications include : power indicators, economic indicators, weight and dimensions indicators , exhaust pollution indicators.

 1 power  indicators

    Diesel power index is the external work capacity , generally refers to the power, average effective power , mean effective pressure , speed and average speed of the piston .

    ( 1 ) effective power

    Diesel power unit time made known power, power units of kW, kW = 1000N. M / s.

    Cylinder diesel power unit of time in doing is called indicated power . Indicating power consumption in friction loss by subtracting the internal parts , pump gas estranged Yu dynamic torsional mechanical attachment pull power loss after loss , draw power from the engine crankshaft called effective power Pe.

    If the engine crankshaft revolutions per minute of n, the effective power output per crankshaft is We, We = 2 * Since the effective power PI * n/60 * Me (Nm) the diesel generators for Pe = PI * nMe/30000 (kW)

Where Me - effective torque .

    ( 2 ) mean effective pressure

    The average effective pressure is generally eight to compare and assess the performance of various engine power , which is the size of a virtual role in the constant pressure of the piston crown , which is a power stroke of the piston moves made equal done per cycle effective work .

    Active power can also be represented by the formula Pe = i * Vs * Pe * n/30t (kW)

Where i- cylinders ;

    Vs- cylinder working volume , L;

    Pe- mean effective pressure , MPa;

    n - engine speed , r / min;

    t－ the number of strokes of an engine , the four-stroke engine t = 4, the two-stroke engine t = 2.

    Thus Pe = 30 * t * Pe / i * Vs * n

    Visible Pe represents the effective power units cylinder working volume issued. Pe is an important indicator , which shows not only the quality of the work cycle was carried out , but also the size of the mechanical loss in the same conditions , Pe higher the value , the more effective power output of the engine . Value Pe is generally as follows :

    Non- supercharged diesel engine (0 5-O.9.) MPa;

    Supercharged diesel engine (0. 8-3.2) MPa.

    ( 3 ) piston speed and average speed

    ① speed diesel engine crankshaft revolutions per minute , with r / min said . Speed effects on engine performance and structure large, and its scope is very broad. All types of diesel engines speed range varies.

    ② average speed of the piston in the cylinder piston movement Cm catch rate is constantly changing in the middle of a larger trip , near the dead small, only point zero. If the known engine speed n, the average speed of the piston is calculated by the following formula

                              Cm = 2 * Sn/60 = Sn/30 (m / s)

Wherein the stroke S- , M.

    2 . Economic indicators

    Economic indicators generally refers to diesel fuel consumption rate and the rate of oil consumption .

    ( 1 ) Fuel Consumption

    Fuel consumption Fuel consumption for short , which is the number of grams per kilowatt hour of the diesel engine oil consumption of the A unit is g / (kWh). To indicate the power meter per kilowatt -hour fuel consumption indicate fuel consumption called for effective power meter per kilowatt hour fuel consumption rate is called the effective fuel consumption . The former indicates the index represents the economic engine . The latter represents an effective indicator of an oil- economy . Fuel consumption in diesel engines referred to are the product description refers to the effective fuel consumption . After measuring the speed and torque of Me n, and the fuel consumption per hour tGt (kg / h) and the effective power Pe, determined by the following formula effective fuel consumption rate ge, i.e.

    ge = Gt / Pe * 10 ^ 3 [g / (kW.h)]

    Ge value of the diesel engine [g / (kW.h)] range is as follows:

    High-speed diesel engines , ge = 212 ~ 235; low speed diesel engine , ge = 169 ~ 190.

    ( 2 ) the rate of oil consumption

    Diesel engine operating conditions during calibration , the number of grams per kilowatt-hour consumption of oil quantity called oil consumption rate , in units of g / (kW · h).

    Diesel oil is continuously recycled within the machine , the main reason for its consumption is: when the engine is operating oil fleeing into the combustion chamber through the piston or burned by the cylinder valve conduit flow popularity , not burn it with the exhaust gas ; Further , since the part of the crankcase oil atomized or evaporated , and discharged from the crankcase vent . Diesel oil consumption rate is generally 0. 5-4g / (kW.h) around .

    3 Weight and dimensions indicators

    Engine weight and dimensions are compact and diesel evaluation as an indicator of metallic materials utilization. All types of diesel engines for the weight and dimensions of the requirements are different.

    ( 1 ) Weight Index

    Weight indicator than the quality of the diesel engine is usually measured . Than quality (gw) , also known as unit power quality , is the ratio of the diesel engine with rated power Pe Net Gw , ie

                                        gw = Gw / Pe (kg / kW)

    Is the so-called weight excluding fuel quality , oil, cooling water and other not directly mounted to the engine main body and the auxiliary attachment device system .

    Than the size of the mass , in addition to engine type and size , structure and related accessories , but also the materials used and the manufacturing technologies.

    ( 2 ) Dimensions Indicators

    Dimensions indicators index , also known as a compact , compact layout means that the overall level of the diesel engine index . Usually diesel power per unit volume to be measured.

    Pv power per unit volume is calibrated engine power Pe and outline the volume ratio V diesel engine , that is

                          Pv = Pe / V (kW / m ^ 3)

Where V = LBH, wherein L, B, H is the maximum engine length, width and height dimensions .

   4 exhaust pollution indicators

    Contains a number of small but very harmful emissions in diesel engine exhaust . They are carbon monoxide, CO, hydrocarbons HC, sulfur dioxide, nitrogen oxides NO and SO2. These combustion products discharged into the atmosphere, polluting the environment and harmful to human health , causing social nuisance .

    As environmental awareness increases, limits on diesel exhaust pollution are also increasingly stringent. National Standard (GB 267-87) China has implemented two restrictions on diesel emissions of NO as follows:

    When Pe> 300kPa time , ge "214g / (kW · h) when , NOx limit of 29g / (kW h.);

    When g, = 214-268g / (. KW h) when , NOx limit of 14-25g (kW · h);

    When ge> 268g / (kW · h) when , NOx limit of llg / (kW · h).