Heat, latent/sensible

Heat gains and losses can be only sensible or sensible and latent. Sensible heat gains result from conduction, convection, and/or radiation. Latent heat gains occur when moisture is added to the space fe.g., from evaporation . 

The process heat duty is the heat required to be added or removed from the proce.ss fluids to create the required change in temperature. This can he in the form of sensible heat, latent heat, or both. 

For example, if total heat duty (sensible heat, latent heat duty, heat losses to the atmosphere) was 1 MMBtu/hr and water was being heated, a heat flux of 10,000 Btu/hr-ft would be used and 100 ft of fire tube area would be required. 

Total heat Sensible heat Latent heat Sensible heat ratio... 

Heat leakage, sensible and latent Convection heat gains, sensible and latent Internal heat gains ... 

Energy possessed by a substance in the form of kinetic energy of its molecules. Gain or loss of heat may result in a rise or fall in temperature of the substance, or in a change of state (solid to liquid to gas). The term heat is sometimes used in industry where temperature is meant. See Latent Heat and Sensible Heat. 

The interfacial boundary condition may be written in terms of the convective heat transfer of sensible heat, latent heat transfer due to evaporation, and, if the surface temperature is high enough, radiant heat transfer. Mathematically, the surface boundary condition is... 

Heat balance—e.g., condensing steam gives up latent heat, or sensible heat, to increase the temperature in the feed preheater. 

Analysis The body loses heat in sensible and latent forms, and the sensible heat consists of convection and radiation heat transfer. At lovy air velocities, the convection heat transfer coefficient for a standing man is given in Table 13-5 to be 4.0 W/m - C. The radiation heat transfer coefficient at typical indoor conditions is 4.7 W/m "C. Therefore, the surface heat transfer coefficient for a standing person for combined convection and radiation is... 

The available heat is defined as the quantity of heat released within a combustion chamber minus (1) the sensible heat carried away by the dry flue gases, and (2) the latent heat and sensible heat carried away in water vapor contained in the flue gases. Thus, the available heat represents the net quantity of heat remaining for useful heating. 

In a first realization, Jahne et al. (1989) forced a periodical heat flux density onto the water surface using a chopped heat source above the water surface. The temperature response at the water surface was detected with point measuring radiometer. In a further implementation of this technique, HauBcckcr (1996) developed the so-called passive controlled flux method that estimates the skin-bulk temperature difference under natural heat flux conditions assuming a surface renewal model. The naturally occurring heat fluxes at the ocean surface (latent, sensible and long wave radiative heat flux) cause the surface temperature to decrease or increase depending on the direction of these fluxes. The net heat flux forces a skin-bulk temperature difference AT across the thermal sublayer, commonly referred to as the cool skin of the ocean (compare Fig. 2). 

FIGURE 4.4 The Earth s annual and global mean energy balance (Kiehl and Trenberth 1997). Of 342 Wm-2 incoming solar radiation, 168 W m-2 is absorbed by the surface. That energy is returned to the atmosphere as sensible heat, latent heat via water vapor, and thermal infrared radiation. Most of this radiation is absorbed by the atmosphere, which, in turn, emits radiation both up and down. (Reprinted by permission of the American Meteorological Society.)... 

To supply the heat necessary sensible, latent, heat of solution, and heat of crystallization. (The last two are sometimes improperly omitted in heat-balance calculations.)... 

Stack (Heat) Loss - Sensible and latent heat contained in combustion gases and vapor emitted to the atmosphere. 

Nitrogen boils at -196°C and allowing for its latent heat and sensible heat to -50 °C it yields 7.9kcal/kg. The latent heat of solvents lies in the range 75-150 kcal/kg. 

Package plants processing up to 9601/h of contaminated solvents are available and solvents containing 15-20% of resin are suitable for recovery in such units. Although no water is introduced into the solvent, this does not mean that the system cannot be used to recover water-wet solvents, although their comparatively high ratio of latent heat to sensible heat means that the operating rate is slower than for dry feedstock. 

Formulation of heat transfer (sensible and latent) from various types of surface to the cloud... 

There are three types of heat storage sensible, latent and chemical reaction heat storage. Latent heat storage is the most important way of storing heat, and is also called phase change heat storage . Latent heat-storage materials have been widely used for about 40 years. 

---