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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
Feeding Technology and Material Handling for Pharmaceutical Extrusion
Published in Isaac Ghebre-Sellassie, Charles Martin, Feng Zhang, James DiNunzio, Pharmaceutical Extrusion Technology, 2018
Liquids can be fed through a variety of pumps (such as gear, piston, and peristaltic pumps), all equipped with a variable speed drive. The mass flow rate can be measured either via a mass flow meter with a PID (proportional–integral–derivative) controller or load cells. A PID controller is a control loop feedback mechanism commonly used in industrial control systems. A PID controller continuously calculates an error value as the difference between a measured process variable and a desired setpoint.
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.
Performance analysis and parametric studies on the primary nozzle of ejectors in proton exchange membrane fuel cell systems
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
Jianmei Feng, Jiquan Han, Tianfang Hou, Xueyuan Peng
An experimental test bench was constructed to verify the accuracy of the numerical model, as shown in Figures 7 and 8. Figure 7 shows the diagram of the ejector experimental test system. The working fluid of the experimental ejector was air. The high-pressure primary air was supplied by a variable speed scroll compressor whose exhaust pressure was stable at 16 bar. The pressures of the primary and secondary flow were regulated by two pressure regulating valves, respectively. The ejector outlet pressure was regulated by a needle valve. Three pressure gauges were used to measure the primary, secondary, and outlet pressures of the ejector. The pressure gauge used for measuring primary flow pressure was a pointer pressure gauge with a measuring range of 0–16 bar. Moreover, the pressure gauge used for measuring pressures of secondary flow and outlet was a high precision electronic pressure gauge with a measuring range of 0–4 bar. A mass flowmeter with a measuring range of 2–60 g/s was used to measure the mass flow rate. The secondary mass flow rate might be quite small in some conditions, and thereby the direct measurement value of the secondary flow could be less than the minimum range of the mass flow rate meter. Consequently, the secondary mass flow rate is obtained indirectly by measuring the mass flow rate of primary and outlet flow, according to Eq. (13):
Modelling and performances assessment of a nanofluids-based PV/T hybrid collector
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Safae Margoum, Chaimae El Fouas, Bekkay Hajji, Stefano Aneli, Marco Giuseppe Tina, Antonio Gagliano
The rise in the mass flow rate increases the electrical and thermal powers. The maximum electrical outputs are achieved with the mass flow rate of 0.012 kg/s, with values of 64.77, 60.46, and 59.24 W for silver/water, silver/EG, and silver/THO, respectively. Similarly, the maximum thermal outputs are 244.0, 102.20, and 62.23 W, for the silver/water, silver/EG, and silver/THO, respectively.