Inlet Air Flow Rate Research Articles

Economic and Experimental Assessment of KCOOH Hybrid Liquid Desiccant-Vapor Compression System

A liquid desiccant dehumidification cooling system is a promising, energy-saving, high-efficiency, environmentally friendly technology that maintains thermal comfort effectively indoors by utilizing renewable energy sources or waste heat to enhance system efficiency. In this research, a small-scale (6 kW cooling capacity) hybrid liquid desiccant air-conditioning system (HLDAC) is proposed to evaluate the dehumidification performance of a non-corrosive potassium formate (KCOOH) solution. For this, four input parameters, namely, inlet air flow rate, inlet desiccant temperature, inlet desiccant concentration, and inlet specific air humidity, were selected. Moreover, the different combinations of experiments were designed by employing response surface methodology (RSM) to evaluate the dehumidification performance parameters, namely, dehumidifier latent heat load, coefficient of performance of hybrid system, and moisture removal rate (MRR). Further, a comparative performance analysis between the hybrid system and a standalone vapor compression system (VCS) unit was carried out. The result showed a remarkable increase in coefficient of performance, which was observed at about 28.48% over the standalone VCS unit. Furthermore, the economic assessment of the proposed hybrid system is presented in this paper. Finally, from the economic analysis, it was concluded that the hybrid system had a payback time of 2.65 years compared to the VCS unit.

Multi-objective optimization of U-type air-cooled thermal management system for enhanced cooling behavior of lithium-ion battery pack

The forced air cooling of U-type BTMS (battery thermal management system) with 12 prismatic lithium-ion batteries is considerably improved by adjusting the distribution of battery spacing and/or the tapered inlet/outlet manifolds. The temperature and velocity distributions of BTMS with an inlet temperature of 25 °C and various inlet airflow rates are calculated by computational fluid dynamics (CFD). High inlet airflow rate reduces the average temperature of the hottest battery (Tave,max) but increases the maximum average temperature difference between batteries (ΔTave,max), and vice versa for low inlet airflow rate. Multi-objective optimization using Nelder-Mead algorithm combined with CFD is performed to minimize the objective functions including ΔTave,max, Tave,max, and power consumption of fan without changing the BTMS volume. Taking an inlet airflow rate and independent battery spacings as design variables (13 variables), the Tave,max and ΔTave,max of optimized module are reduced to 38.2 °C and 0.3 °C, respectively, with a power consumption of about 1.51 W. Taking a linearly dependent battery spacing, inlet airflow rate, and tapered inlet/outlet manifolds as design variables (3 variables), the multi-objective optimization is carried out in short time and the power requirement of fan is reduced to 1.05 W without sacrificing the cooling performance of U-type BTMS.

Experimental study of propane heat pump system with secondary loop and vapor injection for electric vehicle application in cold climate

In order to solve the problem that the driving range of electric vehicles (EVs) is reduced due to heating in cold climate, and the traditional R134a needs to be replaced by more environmentally-friendly refrigerants, a novel solution of coupling the secondary loop and vapor injection technology (SL + VPI) was proposed. Although propane has high flammability, it is still considered a promising alternative because of its low global warming potential (GWP), high performance, and less charge mass. The impacts of VPI technology, ambient temperature, waste heat recovery power, compressor speed, indoor inlet air flow rate, and charge mass on the heat pump system performance have been experimentally studied. In addition, the heating performance and driving range improvement of different heat pump systems were compared. The results show that at −20 °C ambient temperature, the propane SL + VPI system was second only to CO2 direct heat pump system; its heating performance was 33.3–37.4 % greater than the propane direct heat pump.

Design and performance evaluation of an innovative salt hydrates-based reactor for thermochemical energy storage

Thermochemical energy storage (TCES) with salt hydrates has attracted much attention due to its high energy storage density, low regeneration temperature, and long-term storage without energy loss. As a key component of the TCES system, the reactor has a major influence on the system performance. The traditional reactor has problems of non-uniform reaction and easy liquefaction of salt hydrates. To address the above issues, in present paper, it designed a novel reactor which could disperse the air flow to increase the contact area between the air and the salt hydrates for more uniform reaction. The air outlet channel extended into the salt bed, facilitating fast removal of water vapor generated by dehydration, which could reduce the possibility of salt liquefaction. Compared with the existing reactor, the novel reactor reduced the reaction time by 26 % and increased the thermal efficiency by around 2.5 % under the same conditions. Then the inlet air temperature, inlet air flow rate, material porosity and parameters of reactor geometry were investigated to optimize the performance of the reactor. It was found both the thermal efficiency and reaction time were most sensitive to the inlet air temperature. When the inlet air temperature increased from 353 K to 365 K, the reaction process was shortened by 35.36 % and the charging efficiency increased by 15 %. In addition, it was found there was an optimal length of the outflow channel (ha = 0.17 m) with which the reaction time was the shortest and the thermal efficiency was the highest.

Preparation of Rice Bran Protein (RBP) Powder Using Spray Drying Method at the Optimal Condition and Its Protein Quality

Rice bran is a by-product of the rice milling process. It contains a high concentration of protein. Rice brans are frequently utilized as feed cattle, fertilizer, and fuel. However, their application as human nutrition supplements is uncommon, and the necessary process for this purpose is yet to be established, including the drying process. This study aims to evaluate the effect of the spray-drying parameters, the inlet temperature, inlet flowrate, and inlet air flowrate, on rice bran protein (RBP) powder and optimize it using response surface methodology (RSM). A thermal water-based extraction method was utilized prior to the drying process. The correlation between the spray-drying parameters, i.e., the inlet temperature (120 to 210 °C), feed flowrate (5 to 55%), and air flowrate (246 to 670 L/h), and the RBP yield were investigated. The quality of the RBP powder was evaluated based on acid amino profiling in the mixture through de novo peptide sequencing. The optimized operating conditions for the maximum yield of RBP powder (25.7 g RBP/100 g RRB) are 178 °C, feed flowrate of 25%, and air flowrate of 450 L/h. The main peptides that contribute to RBP powder protein are globulin and glutelin; meanwhile, prolamin is believed to degrade during the drying process. The process also produced protein sugar, helping to produce fine particles powder without the drying agent.

The preparation and characterisation of tasteless core-shell clarithromycin microcapsules

This study aims to fabricate core-shell clarithromycin (CAM) microcapsules to cover up the bitter taste of CAM by spray drying with aqueous polymer dispersion. Water dispersion of Eudragit EPO and Surelease® were innovatively used to encapsulate CAM into microcapsules via a one-step spray-drying method. The inlet air temperature, airflow rate, CAM-polymer ratio, and particle size of CAM were optimised based on drug content and T6% (the time taken for the drug to release equal to 6% w/w). The powder properties were assessed by measuring particle size and microstructure using SEM, FT-IR, and PXRD. Furthermore, selected batch was assessed for their drug content, encapsulation efficiency, in vitro release, bitterness, and stability studies. EPO-Surelease® (1: 4) microcapsules had an average diameter (D50) of 37.69 ± 3.61 μm with a span of 2.395. The drug contents and encapsulation efficiency of EPO-Surelease®(1:4) were 10.89% and 63.7%, respectively. EPO-Surelease® (1:4) microcapsules prepared by spray drying with aqueous polymer dispersion can effectively mask the bitter taste of CAM.

Comparative Study on Theoretical and Numerical Calculations of Mass Flow Rate through Opening of Compartment

In this study, stratified, well-mixed, and simplified theoretical model equations and Fire Dynamics Simulator (FDS) were used to calculate the mass inflow, outflow and neutral height to determine the usefulness of previously proposed simple formulas for the calculation of the mas flow rate through openings of compartments in case of fire. The mass flow rate through the opening was evaluated for two conditions, i.e., a fire inside the compartment and no fire, with a high-temperature homogeneous mixture filled inside the compartment. The height of the neutral plane calculated using the theory and FDS under the condition of fire inside the compartment well obeyed the trend of the experiment. In particular, the FDS results for the neutral plane height and inlet air mass flow well agreed with the experiment. However, for the inlet air mass flow rate, the theoretically obtained stratified and well-mixed model equations overestimated the mass flow variation trend according to the increase in opening width. The results of the stratified model equation were the most consistent with the FDS calculation results regardless of temperature, under the condition of a uniform mixture inside the compartment. Regarding the inlet air flow rate, the difference between the theoretical equation result and FDS result was not small. In contrast, for the effluent air flow rate, the results of the simplified formula were the most consistent with the FDS results.

Effects of spray-drying parameters on physicochemical properties of powdered fruits

This review features different powdered fruits with optimal storage stability and physiochemical parameters. Spray-drying parameters, such as temperatures and flow rate, can affect the physical properties of powders. Carrier agents provide powders with various favorable qualities, e.g. good flow rate. Commercial spray-drying of fruit juice knows different carrier agents. 
 The review involved scientific and methodological publications, conference papers, patents, regulatory papers, and Internet resources. They were subjected to grouping, categorization, comparative analysis, and consolidation. 
 Inlet temperature, maltodextrin concentration, and air flow rate of spray-drying increased the powder yield but decreased the moisture content. Inlet temperature, maltodextrin concentration, and feed flow rate affected the solubility. Effects of atomization rate, air flow rate and free flow rate were assessed in terms of yield, moisture content, hygroscopicity, and solubility. 
 The article introduces the fundamentals of spray-drying and describes the effect of each spray-drying parameter on the powder quality. The list of parameters included inlet air temperature, atomization rate, air flow, and feed flow rate. We also evaluated the impacts of various carrier agents on the powder quality. The article contributed to a better understanding of how variable parameters affect the quality of food powders. The results provide the food industry with better choice options to adopt certain parameters for specific production needs.

The Effect of Mixing Chamber Configuration and Submersion Depth on Centrifugal Aerator Performance

Centrifugal aerators are a vital piece of equipment in water treatment. To improve the efficiency and economy of their operation, a study of their mixing chamber structure and submergence depth was carried out using a combination of numerical simulations and experiments. A centrifugal aerator dissolved oxygen (DO) test bench was built and the numerical simulation was compared with the experiment, the inlet air flow rate showing only a 2.23% error, which verifies the reliability of the numerical simulation. The results show that the capacity of oxygen dissolved in the aeration tank increases and then decreases as the relative area ratio (ð) of the mixing chamber increases, reaching the best capacity at ð = 8.38. In the case of different submergence coefficients (β), the gas volume fraction increased by 31.29% on average at β = 0.15; the standard oxygen transfer rate (SOTR) increased and then decreased with the increase of β, with an average increase of 56.6%. Moreover, the oxygenation performance of centrifugal aerators was significantly improved by the reasonable submergence depth and the structure of the mixing chamber.

Numerical Simulation of a Flat-Sheet Membrane-based Dehumidifier with Various Serpentine Flow Channels

In the present analysis, three potential serpentine flow channel designs for a flat-sheet membrane-based dehumidifier are designed and evaluated in terms of performance metrics such as dehumidification rate (DR), approach temperature (AT), pressure drop (ΔP), and coefficient of performance (COP). The dry side inlet air temperature and relative humidity (RH) are set at 27°C and 0%, and the wet side inlet air temperature and RH are fixed at 40°C and 85%. The inlet air flow rates of the dry and wet sides are both controlled in the range of 20-60 L min−1. The simulation results revealed that the geometrical design of the flow channels has a remarkable impact on the dehumidification performance of the dehumidifier. It is outlined that the water vapor concentration and temperature distribution at the outlet of all proposed serpentine flow channels are almost identical, showing the oversized design of the three- and six-inlet serpentine channels. Under the air flow rates of 30 ∼ 60 L min−1, it is seen that the DR, AT, and ΔP of three-, six-, and nine-inlet serpentine channels are in descending order. It is found that the size and quantity of the channel outlets and inlets have a great influence on the pressure drop. Moreover, the dehumidifier with nine-inlet serpentine flow channel can provide the highest COP with a limited increase in the pressure loss. Hence, this channel design can be a good candidate to be implemented in the flat-sheet membrane-based dehumidifier. The findings of this study could be beneficial for the design of novel dehumidifiers.

Modelled annual thermal performance of a 50MWth refractory-lined particle-laden solar receiver operating above 1000°C

The paper reports on the thermal performance of the sub-system for a solar thermal particle technology used to generate high temperature air, including refractory-lined particle-laden receiver, particle separator, particle storage and particle feeder. These assessments are made with a transient mathematical model developed to calculate the heat and mass transfer within the cavity of the receiver together with the thermal losses to the surroundings, incorporating the influence of solar transients during start-up, turndown or shutdown periods. New insights are provided of the influences of the variables of refractory configuration and of the potential operating controller parameters to manage the influence of solar variability on the annual thermal performance of the system, considering the useful thermal gain of hot air. The model is further used to advance the understanding of the sensitivity of the thermal performance to the mass flow rate of inlet air and mass loading of particles in the receiver on the sensible energy harnessed. The influence of the returned air temperature on the receiver thermal performance is also assessed, to provide insights on the suitability of the present configuration to re-heat already hot air in a CST system. Further to this, the thermal outputs are compared with available CFD data for this configuration, and with that reported for a cavity reactor, to provide information on the model validation.

Thermodynamic analysis for a novel steam injection adiabatic compressed air energy storage hybrid system

This paper proposes a new steam injection adiabatic compressed air energy storage hybrid system (SI-ACAES) for the purpose of enhancing the installed capacity and output of ACAES systems. The proposed system preheats and humidifies the inlet working medium of the turbine by adding a saturator and recovering the heat of compression. For better evaluation of the performance of the system, this paper first performs an energy analysis and an advanced exergy analysis on the SI-ACAES system, followed by a parametric analysis. The results suggest that the SI-ACAES system has increased turbine power by 6.63 MW, round trip efficiency by 3.7%, compression heat utilization efficiency by 9.3%, and exergy round trip efficiency by 2.1% compared to the traditional ACAES system. The exergy efficiency increases with throttle valve outlet pressure, but when inlet water flowrate to the saturator (SAT) and external inlet air flowrate to heat exchanger 8 (HEX8) increase, the exergy efficiency begins to increase and then appropriately decreases.

A comprehensive experimental investigation and dynamic energy modeling of a highly efficient solar air heater with octagonal geometry

This research study developed an innovative high-efficiency solar air heater (SAH) employing symmetrical geometry and a flat absorber plate. Also, an experimental setup of the proposed SAH was designed, fabricated and tested during the application in the winter season. Accordingly, comprehensive information including a list of measurement instruments, an experimental procedure, and a measurement strategy, is being presented. As a critical outcome, the maximum difference between ambient temperature and system outlet temperature for three different inlet airflow rates containing 0.046, 0.034 and 0.022 kg s−1 were 10.75, 14.24 and 18.56 °C, respectively. Moreover, the daily thermal efficiency of SAH has been analyzed. The empirical results reveal that the average daily energy and exergy efficiencies of the proposed SAH were 78.73 % and 32.87 %, respectively. Also, based on the results of economic feasibility study, the fabrication of the proposed SAH is cost-effective with a simple payback of 5.17 years, and an internal rate of return of 23.91 %. Finally, time-dependent mathematical modeling was developed, by coding in MATLAB software and solved by analytical methods, to investigate the dynamic heat transfer among system components as well as the hourly thermal performance. To validate the model, the deviation of actual against modeling values was examined by calculating the mean absolute percentage error. The results demonstrate that with an error of less than 3 %, the model has acceptable accuracy at predicting temperature values.

Optimization of alcohol extraction and spray-drying conditions for efficient processing and quality evaluation of instant tea powder from lotus and green tea leaves

Lotus and Green Tea leaves are two frequently used medicinal plants in Vietnam, utilized as food, drink, or in traditional treatments to help with weight loss and cholesterol reduction. The study’s major goal is to determine the parameters of the process preparation in order to generate instant tea powder that satisfies quality criteria for customer demand. Twenty experiments are conducted using the D-optimal model to evaluate the cause-effect relationship and optimize the production process of instant tea powder. Four independent variables are selected for the survey namely alcohol concentration (40%; 50%; 60%), carrier mass (10 g; 20 g; 30 g), inlet air temperature (160 °C; 170 °C) and flow rate (4 rpm/min; 5 rpm/min). The instant tea powder is effectively created and met quality parameters, with a drying performance, moisture content, total phenol and flavonoid content of 29.15%, 4.83%, 45.29 mg GA/g, and 70.68 mg QE/g, respectively. In conclusion, the optimal parameters of the preparation process were identified, which included an alcohol content of 60%, a carrier mass of 10 g, an inlet air temperature of 165 °C, and a flow rate of 4 rpm/min.

RETRACTED: Effect of combined air cooling and nano enhanced phase change materials on thermal management of lithium-ion batteries

The thermal management of a lithium-ion battery (LINB) cell in three dimensions was described in this study. For the thermal control of the LINB, two strategies were used: active and passive. For the passive heat management approach, phase change material (PCM) was employed. The LINB was put in a PCM-filled chamber. Two circular and oval chambers were placed around the LINB. In order to actively manage the heat, the LINB was thermally managed by placing the chamber and the LINB in an air duct. By changing the inlet air flow rate 0.1 cm/s to 0.4 cm/s, the temperature of the LINB, the amount of heat transfer coefficient (CHTR) and the volume fraction (VLF) of the PCM were investigated at different times (0 to 5000 s) for the two chamber shapes. Finite element method and COMSOL software were used for simulation. The results of this study showed that increasing the inlet air flow rate increases the CHTR of the LINB. Also, increasing the air speed caused the VLF of PCM to decrease. Over time, the CHTR increases and also over time, the LINB temperature increases. The hexagonal chamber resulted in a higher quantity of molten PCM than the circular chamber, particularly at t = 1200 s. • 3D investigation of the thermal management of a lithium-ion battery • Utilizing active and passive strategies in the investigation • Putting the battery in a PCM-filled chamber with two different shapes in passive strategy • Obtaining temperature, CHTR and VLF of the PCM in different inlet air flow rate

Simulation investigation on a novel open-loop air cycle heat pump drying system

Different from conventional drying technology, the novel technology of an air cycle heat pump drying (ACHPD) system, using air as its working medium, is proposed to solve the problems of low energy efficiency, HCFC refrigerant use, and so on. A mathematical simulation model is constructed to evaluate system performance under various working conditions, and its verification via experimental results from a constructed test bench produced errors of temperature within ±1.6%, of drying rate within ±0.01%, and of system power within ±7%. Compared with a conventional electric heater drying (EHD) system, the energy-saving rate of the ACHPD system reaches about 15–27% when the mass evaporation rate increases from 0.75 kg h−1 to 3.45 kg h−1. Under set working conditions, an increase of inlet air flow rate (150–400 kg h−1) improved the dehumidification energy efficiency ratio (MER) by about 1%. However, the increase of inlet air temperature (10–40 °C) and relative humidity (30–80%) reduced MER by about 7% and 21% respectively. The efficiency improvements of heat exchanger (0.3–0.8) can improve the energy efficiency of system by 20%; however, the efficiency improvements of expander (0.55–0.8) and compressor (0.4–0.9) can deteriorate the energy efficiency of system by 17% and 36% respectively. These results would provide new technical references for the application of heat pump technology in drying field from a different perspective.

Study on dynamic heat extraction characteristics of heat exchanger tube embedded in thermal flow reverse reactor for heat recovery

In industry, the thermal flow reverse reactor (TFRR) is considered to be an effective means to reduce ventilation air methane (VAM) from fossil fuel operations. The purpose of VAM combustion is either to reduce the emission of greenhouse gas, to recover energy, or both these subjects. The heat exchanger tubes have been embedded on both sides of high-temperature zone of the regenerative oxidizer for heat recovery in this study to improve economy. The mathematical model is established, as well as the effects of inlet methane concentration and air flow rate on dynamic heat extraction characteristics of heat exchanger tubes under periodic conditions are investigated. The results show that sustainable and stable heat recovery can be achieved when the concentration is greater than 0.6 vol.% and the air flow rate is less than 596 m3/h. Heat extraction mainly depends on downstream heat exchange tubes. The asymmetry of heat transfer process between upstream and downstream heat exchanger tubes is analyzed. It is worth noting that the asymmetry is improved at high inlet methane concentration and low air flow rate. The heat recovery efficiency by the bilateral heat exchanger tubes is 61.72% at most, which provides a reliable theoretical basis for the heat extraction mechanism of the heat exchanger embedded in TFRR.

Prediction and parametric analysis of bubble humidifier performance in a polymer electrolyte membrane fuel cell test system by response surface methodology

ABSTRACT Bubble humidifiers are widely used in fuel cell test systems to humidify the gas entering the fuel cell to improve the output performance. In this study, response surface methodology was used for experimental design and testing to investigate the humidification performance of an air bubble humidifier for a 100-kW fuel cell test system. Four operating parameters, the air flow rate, operating temperature, gas pressure, and water level, were considered in this study over ranges of 2000–7000 SLPM, 40–80°C, 1.5–2.5 bar, and 15–45 cm, respectively. The sensitivity analysis of the operating parameters and the combined effects of various operating conditions on the humidification performance were examined. The results showed that at different water temperatures, the relative humidity of the outlet air increased by about 2%–6% as the inlet gas pressure was increased, while the relative humidity decreased by about 3%–5% as the inlet air flow rate was increased. At a water temperature of 60°C and an air pressure of 2 bar, increasing the water level in the low flow rate experiments did not produce any advantages, but increasing the water level at high flow rates had a greater impact on the performance of the humidifier. This work can provide theoretical guidance for the humidity control of bubble humidifiers.

Performance Improvement of a Novel Trapezoid Air-Cooling Battery Thermal Management System for Electric Vehicles

An air-cooling battery thermal management system is a reliable and cost-effective system to control the operating temperatures of the electric vehicle battery pack within an ideal range. Different from most designs of the rectangular battery pack in previous research, this one proposed a novel isosceles trapezoid layout to improve system heat dissipations. The simulation results showed that the trapezoid design delivered better cooling performances than the rectangular one with a maximum temperature reduction of 0.9 °C and maximum temperature difference reduction of 1.17 °C at the inlet air flow rate of 60 L/s. Moreover, the cooling performance was further boosted by an aluminum heat spreader. The boosted design delivers an average Max T (32.95 °C) and an average ΔT (3.10 °C) at five different flow rates, which are 8.8% and 66.1% lower the one without the spreader (35.85 °C and 5.15 °C). Compared with the rectangular design without the spreader, the average Max T and ΔT of the boosted trapezoid design are reduced by 10.4% and 91.9% in addition to a space-saving of about 5.26%.

Experimental study on performance measurement of planar vacuum membrane dehumidifier with serpentine flow channel designs

In recent years, membrane dehumidification, as a novel dehumidification technology, has received many attentions for energy efficiency in air conditioning systems. Its dehumidification technology is characterized by isothermal dehumidification, which can avoid excess energy consumption. This experimental study focuses on the performance measurement of the planar vacuum membrane dehumidifier. Nafion membrane is used in combination with a planar membrane dehumidifier. A vacuum membrane dehumidification method is also employed to investigate the dehumidification performance. Four serpentine flow channel designs, including three-snake, four-snake, five-snake, and six-snake flow channel designs, are tested at the certain values of temperature and humidity and different inlet air flow rates. Different performance indexes, including water collection, dehumidification rate, pressure loss, and pumping power, are investigated. The results show that the amount of water collected by the cold trap increases with boosting the inlet flow rate in the range of 35 l/min to 55 l/min and it has the largest value when the inlet air flow rate is 55 l/min. However, the amount of water collected by the cold trap decreases with further increase of the inlet flow rate in the range of 55 l/min to 65 l/min.