Diesel Engine Power Plant

Fuel tank

Engine Generator

Cooling Tower

Fuel Pump

Cooling Water Pump

Air in

Air out

Four-Stroke Cycle Engine: An engine that completes one cycle in tworevolutions of the camshaft.

IntakeCompressionPowerExhaust

intake compression power exhaust

Two-Stroke Cycle Engine: An engine that completes one cycle in onerevolution of the camshaft.

Intake & CompressionPower & Exhaust

Exhaust port Exhaust port

Intake port Intake port

Intake & Compression Power & Exhaust

Engine Performance

1. Heat Supplied by Fuel (QS)QS = mF x HV KJ/hr

Where: mf – fuel consumption in kg/hrHV – heating value of fuel in KJ/kg

KW4(60)

Nn'LDPIP

2mi

2. Indicated Power (IP)

Where: Pmi – indicated mean effective pressure, KPaL – length of stroke, mD – diameter of bore, mN = (RPM)/2 For 4-stroke single actingN = (RPM) For 4-stroke double actingN = (RPM) For 2-stroke single actingN = 2(RPM) For 2-stroke double acting

KW4(60)

Nn'LDPBP

2mb

3. Brake Power (BP)

KW60,000

TN2BP

Where: Pmb – brake mean effective pressure, KPaL – length of stroke, mD – diameter of bore, mN = (RPM)/2 For 4-stroke single actingN = (RPM) For 4-stroke double actingN = (RPM) For 2-stroke single actingN = 2(RPM) For 2-stroke double acting

Where: T – brake torque in N-mN – no. of (RPM)

4. Friction Power (FP)FP = IP - BP

5. Indicated Mean Effective Pressure (Pmi)

KPa L'SA'

Pmi

Where: A’ – area of indicator card, cm2

S – spring scale, KPa/cmL’ – length of indicator card, cm

6. Brake Torque (T)T = (P – tare)R N-m

Where: P – gross load on scale, Ntare – tare weight, NR – length of brake arm, m

7. Piston Speed (PS)PS = 2LN m/min

8. Displacement Volume (VD)

secm

PBP

V

secm

PIP

V

secm

4(60)Nn'LD

V

3

mbD

3

miD

32

D

9. Specific Fuel Consumption

a. Indicated Specific fuel consumption

hr-KWkg

IPm

m Ffi

b. Brake Specific fuel consumption

hr-KWkg

BPm

m Ffb

c. Combined Specific fuel consumption

hr-KWkg

GPm

m Ffc

Where: GP – Generator power

10. Heat Rate (HR)a. Indicated Heat Rate (HRi)

hr-KWKJ

IPQ

HR SI

b. Brake Heat Rate (HRb)

hr-KWKJ

BPQ

HR Sb

c. Combined Heat Rate (HRc)

hr-KWKJ

GPQ

HR Sc

11. Generator Speed (N)

RPM n

120fN

Where: n – number of generator poles (usually divisible by 4)

12. Mechanical Efficiency (m)

100% xBPGPgη

100% xIPBPmη

13. Generator Efficiency (g)

14. Indicated Thermal Efficiency (ei)

100% xQ

3600(IP)e

Si

15. BrakeThermal Efficiency (eb)

100% xQ

3600(BP)e

Sb

16. Combined Thermal Efficiency (ec)

100% xQ

3600(GP)e

Sc

17. Indicated Engine Efficiency (i)

100% xee i

i

18. Brake Engine Efficiency (b)

100% xeeb

b

19. Combined Engine Efficiency (c)

100% xeec

Where: e – cycle thermal efficiency

20. Volumetric Efficiency (v)

100% xVolument Displaceme

n drawn air of volume Actualηv

s

h

h

ssh T

TBB

PP

21. Correction Factor for Non Standard Condition

Considering Pressure and Temperature Effects

Considering Temperature Effects alone

s

hsh T

TPP

Considering Pressure Effects alone

h

ssh B

BPP

Note: From US Standard Atmosphere

K10006.5h

-TT

Hg mm 1000

83.312hBB

sh

sh

Where:

P – power, KWB – pressure, mm HgT – temperature,Kh – elevation, meters

Subscript:s – refers to sea levelh – refers to the elevation

ENGINE HEAT BALANCE

Qs = Q1 + Q2 + Q3 + Q4

Where:Q1 – heat converted to useful workQ2 – heat loss to cooling waterQ3 – heat loss due to exhaust gasesQ4 – heat loss due to friction, radiation and unaccounted for

Q1 = 3600(BP) KJ/hrQ2 = mwCpw(tw0 – tw1) KJ/hrQ3 = Qa + Qb

Qa = mgCpg(tg – ta) KJ/hrQb = mf(9H2)(2442) KJ/hrQ4 = Qs – (Q1 + Q2 + Q3) KJ/hr

EngineQs

Q2 Q3

Q1

Q4

Qs = Q1 + Q2 + Q3 + Q4 + Q5