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Application
Published in Benny Raphael, Construction and Building Automation, 2023
The amount of heat absorbed is calculated using the well-known formula: mass multiplied by specific heat multiplied by the change in temperature ∆T. Since the cooling load has a unit of power and not energy (it is energy per unit time), the mass should be replaced by the mass flow rate, that is, the mass flowing per unit time. Mass flow rate is equal to volumetric flow rate multiplied by density. Therefore, cooling load supplied by a coil circulating chilled water is calculated using the formula: Q=CpρGΔT Where, Q is the cooling load in Watts, Cp is the specific heat of water = 4,200 J/kg/deg, ρ is the density of water = 1000 kg/m3, G is the chilled water flow rate in m3/s, and ∆T is the difference in temperatures of supply and return water.
Energy and the First Law of Thermodynamics
Published in Kavati Venkateswarlu, Engineering Thermodynamics, 2020
Open systems, unlike closed systems, essentially involve fluid and hence, energy flow related to the fluid flow can be expressed in the rate form with the use of mass flow rate m˙ and volume flow rate V˙. Mass flow rate is defined as the amount of mass flowing across a cross-section per unit time (kg/s), whereas volume flow rate is the volume of fluid flowing across a cross-section per unit time (m3/s). Then the mass flow rate is given by m˙=ρV˙=ρAV
Laboratory Studies on Underground Coal Gasification
Published in Vivek Ranade, Sanjay Mahajani, Ganesh Samdani, Computational Modeling of Underground Coal Gasification, 2019
Vivek Ranade, Sanjay Mahajani, Ganesh Samdani
The dimensions of this cavity were chosen on the basis of the data available in the literature. Figure 5.18a shows the schematic diagram of aluminum cavity setup. As shown in the figure, the top portion of the cavity roof is subjected to a high temperature by means of a heating tape/coil, i.e., UCG of nonspalling coals. In order to maintain the adiabatic conditions, the whole cavity is insulated with the help of glass wool. At the start of the experiment, oxygen gas was passed through the cavity at a known flow rate. The flow rate was controlled by an automated mass flow controller. The roof of the cavity is externally heated to maintain the specified temperature. The supply to the heating element was controlled based on the temperature at a specific position. The uniform roof temperature is assured by measuring the temperature at another location of the roof. The temperature at the outlet was continuously measured with the help of a thermocouple. The temperature at the cavity outlet gives information on how much heat is carried by the oxygen gas from the cavity roof to the outlet. Once a steady state is attained, the temperature at the outlet is noted down against the feed flow rate and cavity roof temperature. The procedure is repeated for different sets of feed flow rates and roof temperatures.
Experimental and Numerical Investigation on Flow Boiling in a Small Semi-circular Channel of Plate Once-Through Steam Generator
Published in Heat Transfer Engineering, 2021
Xiaofei Yuan, Lixin Yang, Zemin Shang
Schematic diagram of the experiment setup is shown in Figure 1. Deionized water is pumped from water tank to the preheater and then to the experimental test section. The flow boiling of deionized water occurred in the test section. The vapor–liquid mixture enters the condenser and finally flows back to water tank. Twelve heating rods with each power of 250 W are placed into the preheater to provide the subcooled water. Twenty-eight heating rods with each 250 W are located into the base of test section to turn subcooled water into vapor. The outlet pressure is adjusted by safety valve and the back pressure valve. The pulse damper relieves pressure fluctuations. The mass flow rate is measured by the mass flowmeter. Temperatures and pressures of inlet and outlet are obtained by temperature sensors and pressure sensors, respectively. Wall temperatures along the path are measured by thermocouples.
Experimental investigation on the effect of expansion valves in a dual evaporator ejector refrigeration system using R134a and R456a
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021
The mass flow rates (10) in the system were measured by the Coriolis flow meter at the outlet of the ejector. The change of 10 depending on ER is shown in Figure 5. As can be seen in Figure 5, the 10 increased as the ER increased. The variables used to calculate the mass flow rate are density, velocity, and surface area. Since the surface area is constant, two basic parameters influence the mass flow rates. Due to the ejector structure, the velocity of the high-pressure liquid refrigerant, which is throttled from the primary side, increases. Therefore, the ejector increases the velocities and mass flow rates. It was found that DEES-STXV had higher mass flow rates than DEES-DTXV. The main reason for this is that DEES-STXV had higher compressor inlet temperatures and consequently higher refrigerant densities. For instance, when the ER was 0.5, the 10 obtained from DEES-STXV was 70% higher than that obtained from DEES-DTXV. This difference was 64% in case R456a was used as the refrigerant in the system. In DEES-DTXV, the inlet pressure of the evaporator#1 was higher, accordingly, the mass flow rates would be higher due to the increase in the pressure in the ejector outlet.
Comprehensive Data Set of Single Particle Combustion under Oxy-fuel Conditions, Part II: Data Set
Published in Combustion Science and Technology, 2021
Nikita Vorobiev, Sarah Valentiner, Martin Schiemann, Viktor Scherer
In addition to the optical measurement (described in detail in part I) partially reacted particles were extracted from the reactor with a sampling probe (see Figure 4). Fast quenching of all gas-particle reactions is mandatory to determine the sampling point precisely. Therefore, nitrogen is added at the probe tip as quenching gas. The mass flow is defined by a mass flow controller. The probe is tempered with an oil thermostat connected to an external cooling circuit. Particle is sampled from the gas phase by a coalescing gas filter with a PTFE filter element (pore size < 2 μm). In front of the diaphragm pump, a bypass valve is installed to control the total flow rate.