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Properties of Pure Substances
Published in Kavati Venkateswarlu, Engineering Thermodynamics, 2020
The amount of heat required to cause a phase change is called latent heat. Latent heat is also defined as the amount of energy absorbed or released during a phase change process. The amount of heat absorbed during the melting or the amount of heat released during freezing is called the latent heat of fusion. The amount of heat absorbed during vaporization or the amount of heat released during condensation is called the latent heat of vaporization. The magnitudes of latent heat depend on temperature or pressure at which phase change takes place. For water, at 1 atm pressure, the latent heat of fusion is 333.7 kJ/kg and the latent heat of vaporization is 2256.5 kJ/kg. From this, it is stated that at 1 atm pressure, solid ice absorbs 333.7 kJ/kg of energy to melt into liquid water; similarly, water releases the same amount, i.e., 333.7 kJ/kg, to freeze into ice.
Boilers
Published in A.J. Pansini, K.D. Smalling, Guide to Electric Power Generation, 2020
If heat is added to water at 212°F, the water changes its physical state and turns gradually to vapor, or what is known as steam. This change requires 970.2 Btu for one pound of water at the boiling point changed into steam of the same temperature and at atmospheric pressure. The 970.2 Btu is known as the heat of vaporization for atmospheric conditions. The term “latent heat” is applied to any heat added to a substance when it does not result in a change in temperature.
Thermal Energy Storage Systems
Published in Scott Dunning, Larry S. Katz, Energy Calculations & Problem Solving Sourcebook, 2020
Latent heat—the amount of heat that is added or removed from a substance or thermodynamic system during a change of state while its temperature does not change. Example: Latent heat is added to a volume of water in a solid state, and its temperature remains 32°F while the water changes from a solid to a liquid state.
Sea temperature variation associated with the 2021 Haiti Mw 7.2 earthquake and possible mechanism
Published in Geomatics, Natural Hazards and Risk, 2022
Lu Zhang, Meng Jiang, Feng Jing
Latent heat (also known as latent energy) is the absorbed or released energy during the substance from one phase to another at a constant temperature. In the budget of the sea surface, latent heat flux and sensible heat flux are defined as the flux of heat carried by the evaporated water and the flux of heat from the sea due to conduction respectively (Stewart 2009). Latent heat flux is mainly influenced by wind speed and relative humidity while sensible heat flux is influenced primarily by wind speed and air-sea temperature difference. The EFLUX and HFLUX datasets from the second Modern-Era Retrospective analysis for Research and Applications (MERRA-2) with a spatial resolution of 0.5°×0.625° have been analyzed to study the characteristics of oceanic heat flux variation associated with the earthquake. The datasets provide reliable quality for monitoring various ocean-atmospheric parameters in open water (Gelaro et al. 2017). The 9-km gap-filled Chl-a data merged from the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi National Polar-orbiting Partnership (SNPP) and National Oceanic and Atmospheric Administration (NOAA)-20 have also been analyzed in this study (https://coastwatch.noaa.gov/cw_html/cwViewer.html). This dataset using the Data Interpolating Empirical Orthogonal Functions (DINEOF) method has high data quality with consistent statistical property and accuracy globally (Liu and Wang 2019).
Evaluation of a roadway thermoelectric energy harvester through FE analysis and laboratory tests
Published in International Journal of Sustainable Engineering, 2021
Amid Tahami, Mohammadreza Gholiakhani, Samer Dessouky, Arturo Montoya, A. T. Papagiannakis, Luis Fuentes, Lubinda F. Walubita
(3) A fin-equipped heat sink with dimensions of 18 × 10 × 5 cm was used to lower the temperature at the cold side of the TEGs, and hence, increase the power output. Heat sinks are filled with water or some other liquid for cooling purposes. However, water is not the ideal cooling medium, despite its high latent heat of fusion (i.e., 334 J/Kg). The latent heat of fusion is defined as the amount of heat absorbed/emitted when a material changes phases (e.g., solid to liquid and vice versa). In this study, a microencapsulated phase change material (PCM) in a powder form was used to fill the heat sink. Under latent conditions, PCMs allow considerable heat absorption without an increase in temperature. Selecting a PCM with a transition temperature near the temperature at the lower pavement layers (i.e., 18–19°C) allowed maintaining the temperature of the cold side of the TEGs relatively constant (Figure 4) (Wang et al. 2016; Souayfane, Fardoun, and Biwole 2016). There has been a multitude of PCM material applications, such as for example in the thermal management of buildings, heat pump insulation, and spacecraft thermal controls (Souayfane, Fardoun, and Biwole 2016).
Investigation of utilizing carbonized lotus root as photothermal material in the solar steam generation system
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
La Zhang, Changchang Sha, Bingbing Li, Wenju Wang
There are several factors that affect the calculation of solar thermal conversion efficiency: temperature, humidity, airflow, and evaporation area in the laboratory test environment. It is worth noting that m is the net WER after subtracting the WER of the water evaporation system in the dark environment, so that the influence of the environment can be eliminated. Latent heat is the enthalpy of the phase change, which varies from 2453 to 2265 kJ kg−1 from 20°C to 100°C.