What is SFC in IC engine?

In engine tests, the fuel consumption is measured as a flow rate—mass flow per unit time m˙f. A more useful parameter is the specific fuel consumption (sfc)—the fuel flow rate per unit power output.

What is the importance of BSFC in diesel engine?

Brake-specific fuel consumption (BSFC) is a measure of the fuel efficiency of any prime mover that burns fuel and produces rotational, or shaft power. It is typically used for comparing the efficiency of internal combustion engines with a shaft output. It is the rate of fuel consumption divided by the power produced.

Why SFC varies with velocity and altitude?

SFC is a measure of fuel consumed per thrust produced. As altitude increases air mass flow into engine decreases, thrust also decreases for same throttle setting. For example at 33000 ft engine will produce only one-third thrust compared to SL. So, SFC increases at altitude.

Why is Bmep important?

BMEP is a function of temperature of the gases in the cylinder. To increase the temperature you need to burn more fuel, thus making more heat. Or another way is to make better use of the existing fuel. Torque is a function of BMEP and displacement only.

What is the purpose of super charging?

The objective of supercharging is to increase the charge density of the working medium (air or air-fuel mixture), by any means and with the help of a suitable system, before it enters the work cylinder, i.e., to precompress the charge.

Why does BSFC decrease with engine speed?

The decrease in BSFC is due to the better physical and chemical properties of fuel which assisted in improving combustion at low engine speeds. On the other hand, at high speeds, the friction heat losses occur and combustion deteriorates which increases the BSFC.

How do you lower SFC?

Increasing overall pressure ratio on jet engines tends to decrease SFC. In practical applications, other factors are usually highly significant in determining the fuel efficiency of a particular engine design in that particular application.