Atmosphere specific heat

For each specific appHcation of a mbber compound as an iasulating material, there is a minimum value of resistivity below which it does not function satisfactorily. In addition, iasulating compounds are required to withstand the effect of water, moist atmosphere, or heat without their resistivity values falling below a satisfactory level. Insulation resistance measurements frequently serve as useful control tests to detect impurities and manufactuting defects ia mbber products. 

Available data on the thermodynamic and transport properties of carbon dioxide have been reviewed and tables compiled giving specific volume, enthalpy, and entropy values for carbon dioxide at temperatures from 255 K to 1088 K and at pressures from atmospheric to 27,600 kPa (4,000 psia). Diagrams of compressibiHty factor, specific heat at constant pressure, specific heat at constant volume, specific heat ratio, velocity of sound in carbon dioxide, viscosity, and thermal conductivity have also been prepared (5). 

K = Specific heat ratio, at inlet conditions given for some substances in Table 1. Note Published values of K at 15 °C and one atmosphere may be used. If K is unknown, a conservative value of K = 1.001 may be used, in which case the factor C = 315. Note that a correction for non-ideal gases may be necessary. 

Calculate the ideal available energy produced by the discharge to atmosphere through a nozzle of air stored in a cylinder of capacity 0.1 m at a pressure of 5 MN/ml The initial temperature of the air is 290 K and the ratio of the specific heats is 1.4. 

Latent heat is the energy associated with phase changes. Evaporation of water requires an energy input of 2.5 x 10 J per kilogram of water at 0°C, almost 600 times the specific heat. When water vapor is transported via atmospheric circulation and recondensed, latent heat energy is released at the new location. Atmospheric transport of water vapor thus transfers both latent and sensible heat from low to high latitudes. 

Bhattacharya and Gedanken [11] have reported a template-free sonochemical route to synthesize hexagonal-shaped ZnO nanocrystals (6.3 1.2 nm) with a combined micro and mesoporous structure (Fig. 8.1) under Ar gas atmosphere. The higher porosity with Ar gas has been attributed to the higher average specific heat ratio of the Ar which leads to higher bubble collapse temperatures. With an intense bubble collapse temperature, more disorder is created in the product due to the incompleteness of the surface structure that led to greater porosity. Importance of gas atmosphere has been noted when the same process was carried out in the presence of air which results in the formation of ZnO without any porosity. 

An emergency relief valve is installed on a reactor to relieve excess pressure in case of a runaway reaction. The lines upstream and downstream of the valve are 6 in. sch 40 pipe. The valve is designed to open when the tank pressure reaches 100 psig, and the vent exhausts to the atmosphere at 90° to the direction entering the valve. The fluid can be assumed to be incompressible, with an SG of 0.95, a viscosity of 3.5 cP, and a specific heat of 0.5 Btu/(lbm °F). If the sum of the loss coefficients for the valve and the vent line is 6.5, determine ... 

The temperature profile of a planetary atmosphere depends both on the composition and some simple thermodynamics. The temperature decreases with altitude at a rate called the lapse rate. As a parcel of air rises, the pressure falls as we have seen, which means that the volume will increase as a result of an adiabatic expansion. The change in enthalpy H coupled with the definition of the specific heat capacity... 

The temperature of boiling liquor in the tubes, assuming atmospheric pressure, T[ = (373 + 15) = 388 K. In the absence of any other data it will be assumed that the solution enters at 373 K and the specific heat capacity will be taken as 4.18 kJ/kg K. 

A fire occurs in a space station at 200 kW. The walls can be considered adiabatic and of negligible heat capacity. The initial and fuel temperatures are at 25 °C. Assume the station atmosphere has uniform properties with constant specific heats as given. Assume that the constant and equal specific heats of constant pressure and volume are 1.2 and 1.0 kJ/kg K respectively. Conduct your analysis for the control volume (CV) consisting of the station uniform atmosphere, excluding all solids and the fuel in its solid state. 

FIG. 8 Schematic illustration of the steps in the phase diagram and the energy required for ice starting at — 20 °C to become superheated gas (steam) at 120°C at atmospheric pressure (1 atm). The type and amount of heat (sensible or latent) required to change the temperature or phase are given, where Cp is the specific heat and AH is the change in enthalpy. 

The coffee-cup calorimeter can be used to measure the heat changes in reactions that are open to the atmosphere, qp, constant pressure reactions. We use this type of calorimeter to measure the specific heats of solids. We heat a known mass of a substance to a certain temperature and then add it to the calorimeter containing a known mass of water at a known temperature. The final temperature is then measured. We know that the heat lost by the added substance (the system) is equal to the heat gained by the surroundings (the water and calorimeter, although for simple coffee-cup calorimetry the heat gained by the calorimeter is small and often ignored) ... 

An evaporator, working at atmospheric pressure, is to concentrate a solution from 5 per cent to 20 per cent solids at the rate of 1.25 kg/s. The solution, which has a specific heat capacity of 4.18 kJ/kg K, is fed to the evaporator at 295 K and boils at 380 K. Dry saturated steam at 240 kN/m2 is fed to the calandria, and the condensate leaves at the temperature of the condensing stream. If the heat transfer coefficient is 2.3 kW/m2 K, what is the required area of heat transfer surface and how much steam is required The latent heat of vaporisation of the solution may be taken as being equal to that of water. 

However, two types of systems are sufficienfry important that we can use them almost exclusively (1) liquid aqueous solutions and (2) ideal gas mixtures at atmospheric pressure, hr aqueous solutions we assume that the density is 1 gtcvc , the specific heat is 1 cal/g K, and at any solute concentration, pressure, or temperature there are -55 moles/hter of water, hr gases at one atmosphere and near room temperature we assume that the heat capacity per mole is R, the density is 1/22.4 moles/hter, and aU components obey the ideal gas equation of state. Organic hquid solutions have constant properties within 20%, and nonideal gas solutions seldom have deviations larger than these. 

Flash and Flame. When Lead Azide was shot in a non-expl atmosphere, an intense luminosity was produced. This light emission was greatest in gas of low molecular specific heat, where the latter does not increase with temperature. The luminosity decreases the greater the specific heat and die temperature coefficient. The following gases were examined and found to have this decreasing order of luminosity ... 

Water has a high specific heat, which means that it takes a lot of energy to heat it. Water thus acts as a powerful thermal buffer in the Earth s climate, absorbing heat from the atmosphere during the heat of the day and releasing it at night. 

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