Values Of Mass Flow Rate Research Articles

Comparative Study of the Thermal Performance of Two Thermosiphon Solar Water Heaters System

The aim of this study is to present the comparative results of experimental investigations of the thermal performance of two thermosiphon solar water heaters system (SWHS). The first uses the coconut fiber (CF), a local vegetable and the second, the glass wool (GW), an imported and expensive material, as thermal insulations. The maximum instantaneous efficiencies are, respectively, 65.30 % and 58.7% with glass wool and coconut fiber while the mass flow rate values are, respectively, 0.0098 kg/s and 0.0078 kg/s with glass wool and coconut fiber. In addition, the calculated average values of F’(τα) and F’UL are, respectively, 0.79 and 5.86 Wm-2°C for the coconut fiber collector and 0.8 and 5.26 Wm-2°C for the glass wool collector. The average heat exchanger effectiveness obtained for the two SWHS are superior to 50%. As an environment-friendly and renewable material, coconut fiber is particularly suitable for thermal insulation in order to save energy. The experimental results show the ability of the constructed solar water heater in providing hot water suitable for maternity, hotels, households and encourage its implementation and utilization on a broad scale. The SWHS can be used in any weather conditions.

Experimental investigation of a solar air heater with copper wool on the absorber plate

ABSTRACT The thermal performance of a novel solar air heater was experimentally studied in this paper. For this aim, a new solar air collector was designed using copper wool on its absorber plate to be a selective surface. Hence, the area of absorber plate was enhanced to absorb much amount of heat energy. The experimental study was conducted for both cases (presence and absence of copper wool on the absorber plate) to determine the effect of copper wool on the thermal efficiency of the collector. The mass flow rate values of the study were 0.035 and 0.044 kg/s. The results pointed out that fluid temperature at outlet of collector with copper wool was increased by about 8 to14%. Therefore, these collectors may be suitable for space heating and drying of food applications. However, copper wool caused more pressure loss through the collector by 40% compared to simple case of collector. The thermal efficiency of the collectors was obtained as 34 to 83% depending on experimental variable parameters. Similarly, effective efficiency of collectors was computed to be 24 to 70%. It is found that efficiency of the collector was improved when using copper wool on the absorber plate as well as increasing mass flow rate of air.

Energy and exergy analysis of corrugated plate solar collector by forced convection using two different absorber plate material

In this paper, the experimental analysis of two types of corrugated plate solar collector (CPSC) using water as working fluid has been done. Two similar designs and dimensions of CPSC but different materials of absorber plates have been investigated, the collector1 is copper and collector 2 is aluminium. The performance of energy, exergy and total heat loss coefficient of CPSC were analysed and compared. Thermal performance of CPSC depends on many parameters such as outlet collector temperature, absorber plate temperature, temperature difference, inlet collector temperature, atmospheric temperature, mass flow rate (MFR), solar radiation, wind speed and absorber plate material. The three MFR values of 0.0167 kg/s, 0.025 kg/s and 0.033 kg/s were considered in this experimental setup. The thermal performances of these two types of solar collectors were investigated. Also, a comparison between the performance of these two types of solar collector at various MFR was done. Experimental results show that the use of copper-based CPSC could improve the thermal efficiency compared to the use of aluminium based CPSC. The maximum energy and exergy of copper and aluminium based CPSC was found at MFR 0.033 kg/s. Results show that as the water MFR is increased from 0.0167 kg/s to 0.033 kg/s, the thermal efficiency of collector made of copper and aluminium increases.

Performance of an Orifice Meter Handling Two-Phase (Gas-Liquid) Flow.(Dept. M)

— The two-phase flow rate measurements remain a challenging task due its complexity. There are many factors that affect on the measurement process such as the properties of the two phases and the dryness fraction. In the current study, the two-phase flow through three orifice plates with different beta ratios (orifice diameter to pipe inner diameter ratio) of 0.7, 0.63, and 0.5 installed in a horizontal acrylic pipe with an inside diameter of 60 mm has been experimentally investigated to improve the accuracy of the two-phase mass flow rate measurements. The inlet superficial velocities of liquid and gas phases are rated from 0.8 to 2.4 m/s and from 0.0 to 0.79 m/s, respectively. Also, the average gas volume fraction is rated from 0.0 to 61%. The pressure drop through the three orifice plate was measured and the flow patterns were tackled before and after the orifice plate. The effect of the two-phase flow on the orifice correction factor is studied at different liquid and gas mass flow rate values for the three orifice plates with different beta ratios. Also, a new correlation was introduced for the two-phase correction factor through the three orifice plates.

Investigation of combustion modes and pressure of reflective shuttling detonation combustor

Detonation combustors are considered promising alternatives to conventional combustors because they offer high thermal efficiency and fast combustion. However, especially for the rotating detonation combustor, the theoretical propulsive performance has not been confirmed in experimental studies because the highly unsteady flow field hinders the measurements process. To understand the involved phenomena in more detail, a reflective shuttling detonation combustor (RSDC) with a rectangular combustion chamber was developed. The interior of the chamber can easily be visualized owing to its two-dimensional quality. Utilizing the RSDC, several combustion tests with gaseous ethylene and oxygen were conducted for different values of mass flow rates and equivalence ratios. Combustion modes from the tests were classified into four types based on the fast Fourier transform (FFT) analysis of the luminous intensity of the CH* self-luminescence images captured by a high-speed camera and a band pass filter. Simultaneously, the theoretical total pressure of a conventional isobaric combustor was compared to the static pressure measured at the bottom of the RSDC chamber. For the detonation modes, the ratio between experimentally measured static pressure and the theoretical pressure varied depending on the location in the chamber owing to the distribution of the time-averaged static pressure. Furthermore, the pressure ratio of the detonation modes was up to 18% lower than that of the deflagration mode potentially owing to the flow velocity induced by the detonation waves.

A Comparison of Simplified One-Dimensional and Two-Dimensional Analytical Models for Predicting Metallic Recuperator Performance

Abstract The performance models for high-temperature metallic recuperators considering one and two-dimensional heat transfer are presented. In one-dimensional model, an explicit expression to represent the effect of both the temperature and product of partial pressure and mean beam length on the emissivity is developed using emissivity charts. The effect of upstream and downstream surroundings is neglected. A two-dimensional heat transfer model is developed using zone method along with sum-of-gray-gases approximation to study the effect of upstream and downstream surroundings on performance. The results from the two models are compared. For lower values of inlet flue gas temperatures and higher mass flow rates, one-dimensional model predicts results within 5% of two-dimensional model. One-dimensional model provides a simplified solution for the assessment of recuperator performance but predicts the surface temperature distribution on a relatively lower side for higher inlet flue gas temperatures and low mass flow rates.

Choked Flow Behavior of CO2 Refrigerant Flowing Through the Spiral Capillary Tube

The flow characteristics of CO2 refrigerant are numerically studied for an adiabatic spirally coiled capillary tube employing choked flow conditions. The mass, momentum and energy conservation equations are used to develop a numerical model. The existing model is verified with the published results. The choked flow behavior at various geometric parameters viz. tube diameter and spiral pitch is studied. Similarly, the influence of these parameters on the mass flow rate through the tube is observed. A significant change in mass flow rate is due to a change in tube diameter, whereas a minimal variation is observed with the change in surface roughness and spiral pitch. Moreover, it is observed that the coiling effect has a significant influence on the flow behavior of the spiral capillary tube. As the pressure decreases, from unchoked to the choked pressure in the evaporator by 63.46%, the mass flow rate increases by 9.46% only. The capillary tube choking is circumvented by increasing spiral pitch, tube diameter and decreasing the length of the tube. A unique nomogram is developed that gives the best understanding of choked and unchoked flow conditions, that graphical representation is useful to design the spirally coiled capillary tube. By using that, the choked length is identified for the known mass flow rate, even more, the choked mass flow rate is known for a given tube length. Moreover, for the given tube length and evaporator temperature, a nomogram is useful to the known choked values of mass flow rate and exit values of the evaporator pressure and quality of refrigerant.

Sensitivity Analysis of N Undistinguishable Photovoltaic Thermal Compound-Parabolic-Concentrator Collectors (Partly Covered, 50%) Integrated Single-Slope Solar Distiller Unit

Abstract In the current research, the sensitivity analysis of N alike in parts covered photovoltaic thermal compound parabolic concentrator collectors integrated single-slope solar distiller unit is performed and examined. The analysis is done using computational programming in matlab (month: May and location: New Delhi). The parametric values of potable water and DC electric power outputs have been figured for different values of mass flow rate (MFR), number of collectors (N), packing factor (PF), and water depth (WD). Elaborative observations says that the value of potable water output declines and DC electric power output increases with the increase in MFR for the considered values of N, PF, and WD. Also the values of DC electric power increases by 81.63% if packing factor is increased from 0.4 to 0.6 for the considered values of MFR, N, and WD. Based on the results of all the analysis, sensible and effective conclusions are made.

Characteristic and regulation method of parallel turbocompound engine with steam injection for waste heat recovery

In a parallel turbocompound engine, a power turbine (PT) is fitted in the exhaust pipe in parallel with the turbocharging turbine (CT) for waste heat recovery. In this study, steam is generated using the exhaust heat and injected at the turbines inlet to improve the turbine power and engine performance. Numerical model for the engine cycle is established using commercial software GT-POWER. The model is validated against the experimental results of the turbocompound engine and precisely predicts the engine performance. Based on the model, the impacts of the CT and PT sizes on the performance of the parallel turbocompound engine are evaluated firstly. It is found that variable geometry turbine (VGT) should be applied on PT to regulate the energy distribution between the two turbines at engine off-design condition. Then the influences of steam mass flow rate on the engine BSFC, power and efficiency are investigated. The optimum values of the steam mass flow rate and PT size is closely related to the exhaust temperature. At last, the characteristic and regulation pattern of the steam injected parallel turbocompound engines are compared with series turbocompound engine. In parallel turbcompound engine, the BSFC is decreased by 2.08%–3.28% with steam injection.

Comparative Assessment of the Effect of Thermo-Physical Properties on the Performance of Parabolic Trough Solar Collector

The harmful effects of fossil fuels on the environment and continuous growth in the energy demand across the world due to the prosperous population have made it essential to harness renewable energy through different technologies. The heat transfer fluids used in solar thermal systems are fundamental to enhance the higher effectiveness of solar thermal systems. This paper presents a comparative analysis of the influence of the thermo-physical properties of CuO, Al2O3, and TiO2 waterbased nanofluids on the thermal performance of the Parabolic Trough Solar Concentrator, PTSC. The energy governing equations of nanofluids, coupled with the concentrator’s effectiveness equations were solved using iterative relaxation approach. C++ program is developed to examine the impact of the thermal characteristics of the three water-based nanofluids on the heat distribution and performance of the concentrator with varying sizes of nanoparticle in the range 1% ≤ φ ≤ 10% at 0.2 kg/s mass flow rate value. The results reveal that the heat transfer coefficient is expanding by 20%, 21%, and 14%, and thermal efficiencies are diminishing by 9%, 56% and 33% using TiO2, CuO and Al2O3 respectively, with the density increase by 28 %, the thermal conductivity increase by 23 %, and the specific heat capacity reduce by 30 %. The influence of the thermophysical properties of the water-based nanofluids on the heat transfer coefficient and the efficiency of the PTSC are significant. This work indicates that the suspended nanoparticles significantly change the thermal characteristics of the suspension which determines its applications

Research on thermal hydraulic characteristics of integrated reactor in natural circulation operation under ocean motions

The modified one-dimensional thermal hydraulic program RELAP5/MOD3.3 was developed to simulate the natural circulation characteristics of an integrated reactor. The ocean motions were realized by adding additional acceleration in the source term of momentum equation. The pressure drop and heat transfer correlations of helically coiled tubes were adopted. The effect of natural circulation characteristics on integrated reactor was studied under rolling, heaving and inclined motions. Simulation results show that the core inlet temperature has no significant change under those three ocean conditions. The average fluctuation value of core mass flow rate is less than the steady-state value and decreases with the increasing rolling angle under the rolling motion. Besides, critical period was observed. In the heaving motion, the average fluctuation value of core mass flow rate is equal to the steady-state value which is different from the rolling motion. The steam equilibrium quality changes slightly in different heaving acceleration. In the inclined condition, the core mass flow rate is decreased with the increasing inclined angle and excessive inclined angle will cause the steam unsuperheated and this may affect the performance of the turbine.

Simulations for L-STAR experimental gas-cooled system / CFD-Nachrechnung von L-STAR-Versuchen zur Wärmeübertragung von turbulenten Gasströmungen

Abstract Turbulent heat transfer through gas-cooled systems is a key factor for the improvements of the gas-cooled fast reactors. Within the FP7 European projects GoFastR (European Gas Cooled Fast Reactor) [1] and THINS (Thermal-hydraulics of Innovative Nuclear Systems) [2], numerical tools for the simulation of the thermal-hydraulics of next generation reactor systems were developed, applied and validated for innovative coolants. One of their objects was the L-STAR (Luft - STab, Abstandshalter, Rauheiten) facility, which has been designed and erected at the Karlsruhe Institute of Technology to study turbulent flow behaviour and its heat transfer enhancement characteristics in gas-cooled annular channels under a wide range of conditions. The test section consists of a hexagonal cross-section channel with an inner electrical rod heater placed coaxially. This design represents the flow domain around a single fuel rod in a future GFR. In this paper experimental results of the fluid flow with uniform heat release conditions for the smooth heater rod are considered. Design of the facility allows using various values of heating power and fluid mass flow rates depending on the chosen scenario. The purpose of this study is to create CFD models for the L-STAR facility, which are capable of reproducing the results of reference measurements. The other aim is to find an applicable turbulence model for the GFR relevant cases. Steady-state simulations are performed for selected cases. We also present mesh, structural element and turbulence model sensitivity studies during this work. With these model results it becomes possible to validate our CFD models to be applicable for the ALLEGRO gas-cooled reactor fuel assemblies.

ANALISA PERHITUNGAN BEBAN PENDINGINAN RUANG PERANGKAT INTERNET DI PT. X - SITE KEDATON

Abstract -- The cooling process in the internet device room has an important function in maintaining room temperature so that the equipments in the room stay at the desired temperature. With optimal cooling, the equipments in the room are expected to function optimally. The author analyzes the condition of the internet device room with the research method used is by taking field data and analyzing the calculation of the data using formula formulas obtained from the literature. After calculating the data , then the average value of the Thermal load of the room is 3260 Watt, the average of room temperature is 22.95 0 C, the average enthalpy value in the room is 42.72 kJ / kg.a. Then the enthalpy value of the evaporator is 35.86 kJ / kg.a. Then the average value of the mass flow rate coming out of the evaporator is 0.48 Kg / s. From these calculations it can be concluded that the highest room temperature is at 11.00 AM, the average room thermal load value is at 1.20 PM, then the highest enthalpy value of the room occurs at 11.00 AM, then the highest value of enthalpy of the evaporator occurs at 11.00 AM, and the highest average value of mass flow rate occurs at 1.20 PM.

Analysis of exergetic performance for a solar air heater with metal foam fins

AbstractIn this experimental study, an exergetic analysis is presented for solar air heaters (SAHs) that have absorber plates equipped with different fin arrangements. The following two types of fins were used: solid fins (conventional) and metal foam fins. Longitudinal, staggered, and corrugated fin arrangements in SAHs were investigated under the weather conditions experienced in Baghdad, Iraq in February to April 2018. The exergy efficiency and exergy loss of the SAHs were evaluated for five air mass flow rates ranging from 0.011 to 0.059 kg/s. Based on the exergy analysis, SAHs with metal foam fins are more efficient than those with solid fins. In addition, corrugated metal foam fins introduce more turbulent flow than the other fin configurations. It was found that the exergy loss and the exergy efficiency were directly proportional to the values of solar irradiance and air mass flow rates. At solar noon, the maximum values for exergy change were 127 and 89 W/m2 for air mass flow rates of 0.011 and 0.059 kg/s, respectively.

Determination of cop maximum of cold water loop of heat pump heating system by means of numerical-graphical optimization procedure

The paper presents the energy optimization of the cold water loop of the heat pump heating system using analytical-numerical procedure. The aim of the study is obtain the maximum COP of the heating system by optimum of the wall water mass-flow rate and well pump power. The objective function is the heating system?s COP. All components of the heating system: evaporator, condenser, compressor, circulation pump, and well pump are described by steady-state, lumped mathematical model. The model?s equations are coupled, non-linear, multivariable and algebraic, the solution is feasible using an iterative numerical method. The MATLAB?s program with Gauss elimination and Newton-linearization method is applied for solving the model. The obtained numerical data are presented in 3-D graphics. The optimum value of the cold-well water mass-flow rate is obtained from the graphics or by using a selection algorithm. The results of the study are the adequate mathematical model for energy optimization of the heating system, the numerical algorithm for solving the model and the ultimate goal to obtain the optimum of the power of well pump and compressor.

Experimental Analysis of Solar Dish Concentrators With Cylindrical, Oval, and Conical Cavity Receivers

Abstract Three experimental models including cylindrical, oval, and conical cavity receivers were analyzed and tested to estimate the optimum geometry for parabolic dish collector cavity receivers . The main contribution of this paper is that new experimental models are suggested and examined to strengthen the capability of absorbers of solar thermal dish collectors to absorb solar energy. The models were examined for three values of mass flow rates and five values of inlet temperatures of the heat transfer fluid. The thermal performance was evaluated by estimating the thermal efficiency , exergetic performance , and pressure difference. The results recorded the highest values of and for the conical cavity receivers, equal to , and the lowest values of the pressure drop.

Discrete Element Modeling of Seed Metering as Affected by Roller Speed and Damping Coefficient

Abstract. The development of highly efficient seed metering is required to meet the demands of modern seeding equipment. The discrete element method (DEM) was used to simulate metering of seeds with a fluted roller meter. This approach was chosen due to its capability to accurately represent granular material flow. The contact model selected for the DEM simulation was the linear rolling resistance model. Angle of repose experimental tests and simulations were performed to calibrate the rolling friction coefficient for peas. The calibrated value for the rolling friction coefficient was 0.016. A 192 mm cross-section of an air cart seed roller and housing was defined as the domain of the simulation. Sensitivity analysis showed that simulated mass flow rates were not sensitive to the selected damping coefficients (0.2, 0.5, and 0.8). Sensitivity indicator values varied between -0.049 and 0.088 for the range of damping coefficients and roller speeds studied. The simulated geometry of the seed meter and housing resulted in a steady flow of seeds, with discharged mass increasing linearly. The simulated mass flow rates were 34.0, 72.3, 110.4, 147.3, and 182.0 g s-1 for roller speeds of 10, 20, 30, 40, and 50 rpm, respectively. An experiment was performed to validate the simulation results. The predicted mass flow rate values of the simulation were within 10 g s-1 of the experimental results, with the largest relative error being 16.5%. Keywords: DEM, Damping, Metering, Peas, Rolling friction coefficient, Seed, Simulation.

NUMERICAL ANALYSIS FOR THE EFFECT OF POROSITY ON THERMAL ENERGY STORING AND RELEASING IN THE SPONGY POROUS MEDIUM

Applications of heat transfer and fluid flow through porous media are very capacious, so they have drawn great attention and research. Acoustics, filtrations, and heat storage are examples of the wide application. The technique of the thermal energy storage (TES) to stock heat energy for later use is applied in many applications. Reliable stable low cost can be provided by storage solar thermal energy and undue heat from non-natural sources. A simple low-cost design that can fluently be constructed which uses the available porous media founded in nature is considered in the present study. The present study analytically investigated the effect of faction void of porous media (silicon rubber) on the process of heat transfer through heat storage and on the storage system. The study develops a numerical model to investigate the effect of several parameters, e.g. mass flow rate, bed length, particle diameter and different values of porosity during charging and discharge. The results depict that the amount of thermal energy stored, and the time of storage are affected by the working fluid, its porosity, and mass flow rate. The present model uses water as working fluid and the silicon rubber as storage medium. It is governed by two partial differential equations for these two substances. The conservation equations are applied on the present system for each of them separately. The storage medium and the working fluid are in case of heat exchange process all over.

Thermal performance enhancement of solar air collector using a novel V-groove absorber plate with pin-fins for drying agricultural products: an experimental study

An experimental investigation of a novel V-groove absorber plate with pin-fins on double-pass solar air collector was made to study the enhancement of thermal performance. The objective of this work is to develop a solar air collector for drying agricultural products with enhanced heat transfer rate by employing pin-fins on V-groove absorber plate under varied configurations. The parameters that influence the instantaneous thermal efficiency of the collector are discussed, and obtained results are compared with a conventional V-groove absorber plate for same mass flow rate values. Energy and exergy analyses were also carried out. The results show that the efficiency of the collector depends strongly on the flow rate. Also, it is noted that for a flow rate of 0.035 kg s−1, the novel V-groove absorber plate with pin-fins installed on both sides exhibits extended heat transfer area, thereby a rise in average thermal efficiency by 17.4%.

Achievement of humidification and dehumidification desalination system by utilizing a hot water sprayer and ultrasound waves techniques

An experimental investigation on the solar system for water desalination was conducted according to the methodology of humidification-dehumidification. Tests have been properly designed and constructed to efficiently assess the productivity of fresh water during the three summer months under local weather conditions of Alexandria, Egypt. The heated air is humidified through two sequent stages,the primary stage is achieved through employing a heated water spatter from the evacuated solar collector. The Further stageis employing anultrasonic technique for its highly efficient humidification rate. The findings of fresh water output rate is affected by two main parameters; firstly the mass flow rates of both air and water spray, secondly solar radiation. Furthermore, an investigation of heated water spray flow rate over the total flow rate at four values of 0.175, 0.2, 0.25 and 0.3were done respectively. The maximum amount of daily productivity reaches to 44.8 kg/day with mass flow rate of 0.46 kg/s for air, while hot water spray ratio of 0.3. The ultrasonic humidifier improves the daily productivity by 9.3% at 0.24 kg/s and 14.6% at the maximum value of the air mass flow rate 0.46 kg/s. Economic analysis showed that the fresh water cost is about 0.0144 USD/L.