Question

A set of indicator diagrams cards has been taken for a main diesel engine. Analyze with reference to the following conditions and suggest corrective action in each case:

(a) Higher peak pressure with normal compression pressure.

(b) Normal peak pressure with lower compression pressure.

(c) Higher peak pressure with higher compression pressure.

(d) Normal compression pressure with fluctuating pressure line during expansion stroke after ignition.

Answer 1

Part (a)

The maximum pressure is higher

Pcomp = Normal

Pmax = High

Conclusion = Early injection

Reasons and remedy:

Wrong injection timing: Check the fuel pump timing and adjust as per maker's manual
Incorrect VIT setting: Check and adjust the VIT according to makers recommendations
Leaking fuel injector: Overhaul the fuel valves or change the nozzle

Part (c)

The expansion curve is higher

Pcomp = High

Pmax = High

Conclusion = high expansion curve

Reasons and remedy:

Exhaust valve opening late: Check the timing of the exhaust valve opening and adjust the timing
Engine overload: Reduce the load on the engine

✓ Verified Model Answer (Text Solution)

The maximum pressure is higher

Reasons and remedy:

The expansion curve is higher

Reasons and remedy: