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Water
Published in P.K. Tewari, Advanced Water Technologies, 2020
The specific heat of water is 4.2 J/g°C, which is higher than that of any other common substance. Specific heat is a measure of heat to be added to or released from a substance to change its temperature. This means that 4200 J of heat when added to 1.0 kg of water increases the temperature of water by 1°C. This is a significant amount of heat required to make a small change in the temperature of water. It takes a lot of heat to heat up the water, but once it is hot, it remains hot for a long time. Solids tend to have a lower specific heat capacity. Think of stirring hot soup with a metal spoon. Metal spoons heat up fast. This is because metal has a very low specific heat capacity, so a small amount of heat makes a large temperature change, and water has a high specific heat capacity. Water plays a very important role in temperature regulation, e.g., sweating to dissipate the heat from the human body and control body temperature.
Prologue
Published in Vikram M. Mehta, Natural Decadal Climate Variability, 2020
The Earth’s atmosphere is a gaseous fluid composed of 78% nitrogen by volume, 21% oxygen, 0.9% argon, 0.04% carbon dioxide, and other gases. Water vapor can contribute 0.001% to 5% of the atmosphere’s volume. The total mass of the atmosphere is approximately 5.15 × 1018 kg. The vertical structure of the atmosphere is mainly due to the force of gravity on constituent gases, with approximately 50% of the atmospheric mass below 5.6 kms, 90% below 16 kms, and 99.9999% below 100 kms. The weight of the atmospheric mass above any point on the Earth’s surface is the pressure exerted by the atmosphere above the point, and depends on weather and elevation. The reference standard pressure at sea level is 101,325 Pa (or, in the popular units used by meteorologists, 1,013.25 millibars or hectoPascals (hPa)). The estimated density of air at sea level is 1.2 kg m−3. The specific heat capacity of air at 300 K (26.85°C) temperature is 1,005 J kg−1 K−1. Motions and heat transfer processes, including waves, in the atmosphere are governed by laws of fluid dynamics and thermodynamics. As mentioned in Section 1.2, substantial changes in carbon dioxide and water vapor contents of the atmosphere can make very important impacts on climate even though their relative volumes in the atmosphere are very small.
Energy Storage Systems Based on Compressed Air
Published in Alfred Rufer, Energy Storage, 2017
The specific heat is defined as the energy required to raise the temperature of a unit mass of a substance by one degree. In general, this energy depends on how the process is executed. In thermodynamics, we are interested in two kinds of specific heats: Cv: Specific heat at constant volumeCp: Specific heat at constant pressurePhysically, the specific heat at constant volume Cv can be viewed as the energy required to raise the temperature of the unit mass of a substance by one degree as the volume is kept constant (Q1). The energy required to do the same as the pressure is kept constant (Q2) is the specific heat at constant pressure Cp.
2-D FEM thermomechanical coupling in the analysis of a flexible eRoad subjected to thermal and traffic loading
Published in Road Materials and Pavement Design, 2023
Talita De Freitas Alves, Thomas Gabet, Rosângela Motta
Assuming that there is no heat sources and sinks, the net heat fluxes must be equal to the storage rate of thermal energy: Where is the density of the material, in kg/m3; is the specific heat capacity, in J/(kg⋅°C); and is the partial derivative of the temperature with respect to time. The specific heat capacity is defined by the amount of heat required to cause a change in temperature by 1°C of a unit of mass of the material. Finally, the Fourier's partial differential equation is the simple balance of and , that must be satisfied in every point x for every moment :
Subcritical water pretreatment enhanced methane-rich biogas production from the anaerobic digestion of brewer’s spent grains
Published in Environmental Technology, 2022
William Gustavo Sganzerla, Larissa Castro Ampese, Solange I. Mussatto, Tânia Forster-Carneiro
Finally, a global industrial energy balance was calculated to determine the energy demand of SWH pretreatment based on a subcritical water laboratory plant used for pretreatment [48]. For the energy balance of the subcritical reactor (Eq. 11), the following conditions were assumed: i) steady state; ii) constant pressure; iii) without shaft work; iv) without kinetic energy; v) variation in potential energy neglected; and vi) constant mass [49]. Therefore, the heat required (Q) is the difference in enthalpy (H) (Eq. 12): The enthalpy can be calculated considering that the mass of water >> mass of BSG (Eq. 13). Hence, the specific heat of water () was determined to be 4.178 kJ kg–1 K–1 at 25 °C and 4.285 kJ kg–1 K–1 at 160 °C [48], considering constant pressure.
CFD analysis of the earth air pipe heat exchanger with helical geometry for optimum space utilisation
Published in International Journal of Ambient Energy, 2023
Mahendra Kumar Verma, Vikas Bansal
In previous studies, near the pipe surface due to thermal saturation in the soil, the efficiency of the device deteriorated after a long time. In this analysis, water pipes are used to absorb heat from the surrounding soil as a thermal reservoir that supports operating the device for a long duration. As a heat reservoir, water can be utilised due to its highest specific heat; it can absorb the heat from the surrounding soil without a significant change in its temperature. Figure 13 shows the temperature contour of water inside the aluminum pipe at different time intervals of 6, 12, 18, and 24 h, it is clear from the contour that variation in the temperature of the water can be seen after its continuous performance of 12 h.