Latent heal

Physical and Chemical Properties — Physical State at 15 T7 and 1 atm. Liquid Molecular Weight Mixture Boiling Point at I atm. Decomposes Freezing Point 17, -8,265 Critical Temperature Not pertinent Critical Pressure Not pertinent Specific Gravity 1.2 at 20 °C (liquid) Vapor (Gas) Density Not pertinent Ratio cf Specific Heats cf Vapor (Gas) Not pertinent Latent Heal of Vaporization Not pertinent Heat of Combustion -15,700, -8750 -366 Heat of Decomposition -50, -28, -1.2. 

Steam at atmospheric pressure is saturated at 373 K at which the latent heal... 

Cooling of water can be carried out on a small scale either by allowing it to stand in an open pond or by the spray pond technique in which it is dispersed in spray form and then collected in a large, open pond. Cooling takes place both by the transference of sensible heat and by evaporative cooling as a result of which sensible heat in the water provides the latent heal of vaporisation. 

Latent Caloric, or IIeat of Fluidity.—Black asserted, many years ago, that fluidity was owing to the chemioal combination of matter with a certain amount of heat, whjoh could not be detected by the thermometer. To this he applied the tarm heat of fluidity, or latent heal, assuming that heat, by its chemical combination... 

Energy Losses. Not all of the Btu in the fuel are converted to heat and absorbed by the steam generation equipment. Some of the fuel may be unbumed. leaving carbon in the ash or carbon may be hurried incompletely to form some CO instead of all CO.. Usually all of Ihe H. in the fuel is burned By Tar the greatest heal loss is the loss up the slack. Since the heat in the fuel is determined from a base of ambient temperature, all of the products of combustion must be cooled to the same temperature if all of the heat is to be utilized. Higher temperatures then represent a loss, which is the sum ol lour items (I) the sensible heat in dry Hue gas. (2) the sensible heat in the moisture in the air, (3) the sensible heal in the H 0 in Ihe fuel, and 4) the latent heal of the moisture in the fuel. 

CONDENSATE. A vapor may be reduced to liquid by removal of such portion of Ihe latent heal of evaporation us it may contain. The act is called condensation, and Ihe liquid is condensate. It is the property of vapors that the condensate is dense as compared lo the vapor, which, in condensing, formed it that is, there is considerable shrinkage of volume upon a reversion lo the liquid slate. The thermal condition of the condensate immediately upon formation is that of saturated liquid at the temperature of vapor. See also Distillation. 

In this balance, the assumption is made that the molar heat capacities and the latent heals of vaporization of all components arc identical. It is also assumed that heat losses from the column and heals of mixing are negligible. With these assumptions, the upward vapor flow and the... 

Phase changes often occur at temperatures other than the temperature for which the latent heal is tabulated. When faced with this situation, you must select a hypothetical process path that permits the available data to be used. 

You are writing energy balances for a compound for which you cannot find heat capacity or latent heal data. All you know about the material are its molecular formula (C7H12N) and that it is a liquid at room temperature and has a normal boiling point of 200°C. Use this information to estimate the enthalpy of the vapor of this substance at 200 C relative to the liquid at 25 C (Recall Section 8.3c.)... 

We can have a similar argument for vapor that enters the condenser as superheated vapor at a temperature 7,. instead of as saturated vapor. In this case the vapor must be cooled first to 3 , before it can condense, and this heat must be transferred to the wall as well. The amount of heat released as a unit mass of superheated vapor at a temperature 7,. is cooled to 75, is simply Cf,r[Ty - 7jjt), where Cp,. is the specific heat of the vapor at the average temperature of (Ty + 7sj,)/2. The modified latent heal of vaporization in this case becomes... 

Analysis (a) Tlie modified latent heal of vaporization is... 

Normal Boiling Point, °C Latent Heat of Vaporization hfg, kJ/kg Freezing Point, "C Latent Heal of Fusion hit, kJ/kg Temperature, Density °C p, kg/iri5 Specific Heat Cp, kJ/kg K... 

Has integral heat of solution for the solute (kJ/mol or Btu/lb-mole) fi latent heal of pare solvent, same units as Hos Hit. height of weir on sieve tray (m or ft)... 

Dipole moment 1.83-1.90. Dielectric constant (25 ) 51.7. Latent heal of fusion (mp) 3.025 kcal/mole latent heat of vaporization (bp) 9760 kcal/mole (calc), Crit temp 38Diacidic base. K, (25°) about 9 X 10 7. Forms salts with inorganic acids. Highly polar solvent. Powerful reducing agent. Dissolves many inorganic substances. Misc with water, methyl, ethyl, propyl, isobutyl alcohols. Forms an azeotropic mixture with water, bp 40 120.3°, which contains 55 mole-% (68.5 weight-%) NjH,. LD,g in mice (mg/kg) 57 i.v. 59 orally (Witkin),... 

Water may be sprayed into the gas at such a rate that, on complete vaporisation, it gives the recjuircd humidity. In this case, the temperature of the gas will fall as the latent heal of vaporisation must be supplied from the sensible heat of the gas and liquid. 

Low heal of adsorption (< 2 Of 3 times latent heal of evaporation.)... 

How many pounds of heavy hydrocarbon liquid must be vaporized to cool 700,000 Ib/hr of vapor from 980°F to 630°F Assuming a specific heat of 0.6 for the vapor and a latent heal of vaporization of 90 BTU/lb for the cycle oil ... 

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