Papers by Keyword: Mass Flux

Abstract: The present research targeted the measurement of flue gas flow rates in industrial boiler applications, to improve boiler efficiency in Sri Lanka. This study discussed three methodologies for flow measurement and placed significant emphasis on the benefits of thermal mass flow meters, given their accuracy and reliability, especially within low flow rates. A thorough literature review was conducted to pinpoint critical parameters involved in the generation of boiler performance: flue gas composition and draft regulation. This research spotlights the deficiency in the current measurement practices, hence, a systematic approach to develop, a cost-effective and regionally adaptable solution is presented for the flue gas flow measurement. The investigation validates the proposed measurement techniques by using a combination of theoretical analysis and CFD simulations and demonstrates that the simulated flow rates are close to calculated values, with minimum differences of 0.000461 kg/s. results imply that the optimization of flue gas flow measurement can result in significant enhancements in combustion efficiency. The research ultimately contributes to the betterment of boiler operation practices in Sri Lanka by providing recommendations for future studies and practical implementations to enhance resource management and environmental sustainability within the industrial sector.

Abstract: Magnetohydrodynamics (MHD) flow of Casson fluid over a curved stretching surface with the effects of heat and mass flux conditions are studied. Casson fluid is one of the non-Newtonian fluid. Human blood is taken as example of Casson fluid. The flow, heat transfer and the mass transfer characteristics are found by a curved stretching sheet with flux conditions. The governing partial differential equations are converted into nonlinear ordinary differential using similarity transformations and are solved using the Runge-Kutta Fourth order method along with shooting technique. The effects of pertinent governing parameters on the fluid velocity, the temperature and the concentration are shown with help of the graphs. The Skin frication coefficient and the Nusselt number are calculated numerically. The present results have been good agreement when compared with existing results under some special cases.

Abstract: The problem of material treatment by the beams of particles for non-isothermal conditions is solved analytically. The thermal diffusion is taken into account. The stress and strain evaluation in the treatment zone is carried out using the methods of thermal elasticity theory (for the elastic body) and analogy method in the space of Laplace integral transform (for the viscoelastic body). It is shown that the thermal diffusion is the most essential for the body with small viscosity.

Abstract: Theoretical analysis of unsteady magnetohydrodynamic free convection flow of a viscous incompressible radiative fluid past an infinite vertical plate with constant heat and mass flux is presented. The dimensionless governing linear partial differential equations have been solved using the Laplace transform technique. The exact solutions for the velocity, temperature and concentration fields are derived. The effects of radiation, magnetic field and buoyancy ratio parameters on the velocity and temperature fields are discussed through graphs. It is found that the velocity increases with increasing radiation parameter whereas it decreases with increasing magnetic field parameter for buoyancy assisted flows.

Abstract: The steady state distributed parameter model of heat exchangers in a heat-pump system was established in this paper. The calculating results of refrigerant quantities in the heat-exchangers show that refrigerant charge quantity in heating operating condition is less than that in refrigeration operating condition. Based on the differences of refrigerant mass flux between refrigeration and heating conditions, the exhaust bypass method to improve the operation efficiency of the heat-pump system was presented. And in order to prevent frosting on the surface of outdoor heat exchanger of the air source heat-pump, the solar energy assisted strategy was also applied in the heat-pump system.

Abstract: When designing the centrifugal cooling pump, the people have been accustomed to design the normal clearance of the impeller shroud by mechanical assembly principle only for preventing parts from interference. But in the practice, the shroud clearance magnitude of the cooling pump is very difficult to be confirmed because of either serious leakage or high power consumption. As so far, it hasn’t been specific theory about its magnitude which was designed only by a large of experiment. The boundary-layer thickness theory can be introduced to calculate the impeller clearance magnitude. This method first breached conventional experiment way in determine the shroud clearance magnitude and applied scientific theory to the engineering design. As a result, this method can save a great deal of industrial resources such as manpower, materials and funds, and give the more precise scientific reference to relative research about pump

Abstract: Anofluids are suspensions of metallic or nonmetallic nanopowders in base liquid and can be employed to increase heat transfer rate in various applications. In this work turbulent flow forced convection heat transfer of Al₂O₃-water nanofluid inside an annular tube with variable wall temperature was investigated experimentally. The Nusselt number of nanofluid was obtained for various Reynolds numbers and nanoparticle concentrations at atmospheric pressure. The addition of nanoparticles in water enhances heat transfer coefficient and the enhancement increases with increase in the nanoparticle concentration and flow rate. Experimental results emphasize the enhancement of heat transfer due to nanoparticles presence in the fluid.

Abstract: Calculation of refrigerant quantities in the heat-exchangers of an air-conditioner on refrigeration and heating operating conditions shows that refrigerant charge quantity in heating operating condition is less than that in refrigeration operating condition. The refrigerant control strategies are most important for refrigeration and heat-pump system. Based on the difference of charged refrigerant quantities of the air-conditioning system between refrigeration and heating operating conditions, the exhaust bypass method was presented in order to improve its operation efficiency. This heat-pump system for controlling refrigerant mass flux was analyzed in detail. The results show that the exhaust bypass method has its advantages in controlling refrigerant mass flux for heat-pump system.

Abstract: Fabrics are needed further treatment after dyeing to restore their original mechanical properties by suitable drying/shrinkage process because of wetted and elongated fabrics cannot be used for clothes making. Heating up the dyed fabrics at suitable temperature can restore their original shapes and geometries by releasing the internal stress introduced by dyeing process. Thus, heat setting is a commonly used post-treatment process to stabilize fabric geometrical dimensions and prevent further shrinkage. Hot air jet impingement [1] and moist heat are conventional drying methods for different applications. Despite the well establishments of these drying technologies, most of the applications are for materials like clay and paper, and few on the study of textile materials. In fact that most of the developed heat setting machines used in textile industry are only designed by empirical models and lack of theoretical bases. This situation will obstruct further improvement of the drying technology. In this paper, a theoretical basis heat transfer model is developed for a precise description of a heated air flowing process for heat setting machine design. In the machine design, a better airflow circulation strategy for an efficient drying is addressed. Equations for heat and mass transfer in moist porous materials and theories on thermo- and fluid-dynamics are used to support the machine design. Outcomes from the research are to develop a heat transfer model that provides more precise and effective calculation for heat setting machine design that unavailable from the developed machine prototypes.

Abstract: Because of many advantages that other kinds of bearings can not match, for example high precision and high speed, gas lubricated bearing has been used widely in areas such as ultra-precision machine tool and inertia apparatus. The paper introduced an orifice restrictor externally pressurized spherical gas bearing, which is easily shaped and has bigger stiffness in both axial and radial directions. The paper also introduced a bearing force calculation model based on finite partition of the bearing, in which the influence of the uniform pressure slot also considered.