Солнечная электростанция 30кВт - бизнес под ключ за 27000$

15.08.2018 Солнце в сеть




Производство оборудования и технологии
Рубрики

Fuel Characteristics of Ethanol

As discussed in the earlier section, ethanol was first introduced on a larger scale in the 1970s as a blend in fuel to serve as a replacement for methyl tertiary butyl ether (MTBE). Ethanol has a octane number of 108.6, comparable to 110 of MTBE [7]. Mixing about 10% of ethanol to gasoline can boost the octane number of the fuel [8]. The octane number is a measure of the gasoline quality for prevention of early ignition, which leads to cylinder knocking. Fuels with higher octane numbers are preferred in spark-ignition internal combustion engines (ICEs). An oxygenate fuel such as bioethanol provides a reasonable antiknock value [8]. In addition to a higher octane number, ethanol has broader flammability limits, higher flame speeds and higher heats of vaporization. These properties allow for a higher compres­sion ratio and shorter burn time, which lead to theoretical efficiency advantages over gasoline in an internal combustion engine. A com­parison of important physical properties and fuel characteristics of ethanol, methanol and gasoline is shown in Table 2.1.

Property

Methanol

Ethanol

Gasoline

CH3OH

C2H5OH

C4 — C12

Molecular weight (g/mol)

32

46

~ 114

Specific gravity

0.789 (298 K)

0.788 (298 K)

0.739 (288.5 K)

Vapor density rel. to

1.10

1.59

3.0-4.0

air

Liquid density (g cm-3 at 298K)

0.79

0.79

0.74

Boiling point (K)

338

351

300-518

Melting point (K)

175

129

Heat of evaporation (Btu/lb)

472

410

135

Heating value (kBTU gal-1)

Lower

58

74

111

Upper

65

85

122

Table 2.1 Physical properties and some fuel characteristics of ethanol,

methanol, and gasoline [9].

Property

Methanol

Ethanol

Gasoline

CH3OH

C2H5OH

C4 — C12

Tank Design/pressure

15

15

15

(psig)

Viscosity (cp)

0.54

1.20

0.56

Flash Point (K)

284

287

228

Flammability/ Explosion limit (%) Lower (LFL)

6.7

3.3

1.3

(%) Upper (UFL)

36

19

7.6

Auto ignition

733

636

523-733

temperature (K)

Solubility in water

100%

100%

Negligible

Miscible

Miscible

(~ 0.01%)

Azeotrope with water

None

95% Ethanol

Immiscible

Peak flame

2143

2193

2303

temperature (K)

Minimum ignition

0.14

0.23

energy in air (mJ)

Research Octane num-

108.7

108.6

91-93

ber (RON)

Комментарии запрещены.