Direct Current Fan Research Articles

Effectiveness of thermal energy storage material and forced convection on the regeneration of liquid desiccant using hybrid solar still - An experimental study

Hybrid solar still has been investigated to desalinate the saline water and regenerate the weak liquid desiccant. An influence of thermal energy storage material (waste pieces of black granite) and forced convection (12 V direct current fan) was studied in terms of the water desorbed from the weak liquid desiccant and distilled water output from the saline water in two cases of the experiment. A 40% weight concentrated calcium chloride for Case-I and a 42% weight concentrated lithium chloride for Case-II as a weak liquid desiccant were used for the study and flown over the upper basin, whereas a saline water depth of 1 cm was maintained in the lower basin. The total daily desorbed water for Case-I was 761.33 ml/m2 and 796.00 ml/m2 for Case-II from the weak liquid desiccant. The total daily distillate output achieved for Case-I was 302.67 ml/m2 and 284.00 ml/m2 for Case-II. An increase in the concentration of liquid desiccant for Case-I was 2.42% and 1.37% for Case-II. When hybrid solar still will be used as a regenerator in the liquid desiccant-based solar cooling system, the regenerated liquid desiccant can able to adsorb the latent heat load of 0.1251 kW/d for Case-I and 0.1304 kW/d for Case-II from the humid air. For the bright sunshine hours, the daily average overall efficiency of 20.98% for Case-I and 27.76% for Case-II was obtained for the hybrid solar still.

Development and Evaluation of a Locally Designed Solar Integrated Egg Incubator

There is need for subsistence poultry farmers to maximize chick production to supply the increasing demand for poultry meat. This research developed and evaluated an egg incubator powered by a renewable energy source generated from solar modules. The incubator was incorporated with temperature and humidity sensors which measured and regulated the conditions suitable for the egg incubation. The direct current (DC) heater, sensor, microcontroller and DC fan provided suitable temperature and humidity for the eggs. The developed incubator was evaluated by monitoring the temperature and Relative Humidity (RH) readings over a range of time and the hatchability rate was also evaluated. The temperature within the incubator chamber ranged 37-38°C with an error margin of +0.1oC while the RH ranged between of 30-35% with an error margin of +5%. An average hatchability rate of 92% was obtained from the evaluation of the incubator. The evaluation gave a standardized temperature and relative humidity range of values necessary for incubation of eggs. The study has shown that solar energy could be used to successfully power incubator systems with good hatchability for the whole incubation period.

A novel synthetic jet based heat sink with PCM filled cylindrical fins for efficient electronic cooling

The current electronic industries strive to build an effective cooling solution for modern compact electronic gadgets. The current experimental study, thus, focused on assessing the performance of a heat sink that combines the benefit of active and passive cooling utilizing the synthetic jet and Phase change material (PCM), respectively. The PCM offers a high latent heat value, whereas the synthetic jet induces vortices-based turbulent flow. The cooling characteristics of the heat sink filled with PCM and without PCM are evaluated when subjected to three different operating conditions, which are (i) natural convection, (ii) forced convection using DC fan, and (iii) forced convection using a synthetic jet. The PCM selected for the current study are Eicosane and 1-hexadecanol. It is observed that the inclusion of PCM into the heat sink improved its performance. The multiple-orifice synthetic jet outperformed the single-orifice synthetic jet. The steady-state base temperature attained by multiple orifice synthetic jet is 5 °C lower than that of the synthetic jet with a single orifice. The heat sink cooling performance is best when it is operated at its optimum height measured from the heat sink tip. Heat sink filled with Eicosane subjected to synthetic jet with multiple orifice showed best results, the thermal resistance, heat transfer coefficient and COP is found to be 0.91 K/W, 420.4 W/m2, and 2.1, respectively. The synthetic jet with multiple orifices performed better than the DC (Direct Current) fan operated at the same electrical power input of 0.5 W.

Augmenting the performance of photovoltaic panel by decreasing its temperature using various cooling techniques

The photovoltaic (PV) systems suffer efficiency drop and performance retrogression as their operating temperature increases. This research investigates the routine of polycrystalline silicon PV modules using dissimilar cooling techniques and compares the routine of the PV modules with and without cooling. The available studied PV module output maximum power decreases by up to 0.42% for every one-degree increase in temperature. To investigate the cooling techniques, the experiments were done in July 2021 at the Faculty of Engineering, Ismailia, Egypt (30°35′N 32°16′E). The used cooling methods were; forced air cooling onto the PV module front surface by a direct current fan (case 1); back surface cooling by circulating a coolant in a heat exchanger copper serpentine fixed at the PV module back surface, water (case 2), and copper oxide nanofluid (0.2% mass fraction) (case 3) was used as different coolants in the serpentine; front surface cooling using water as a coolant that flows from small nozzles equally distributed along with the pipe fixes at the PV module frame (case 4). After comparing the recorded results of the four cooling techniques with a conventional system, cooling efficiency, the front PV module surface water cooling technique produced the best results. This technique is easy to be designed, manufactured, and installed. Also, it saves the cost of cleanliness of the surface of the PV module from dirt and dust. These cooling techniques increase the conventional PV system voltage output by 2.7%, 2.43%, 0.9%, and 7.43% and decrease in average temperature by 13.46%, 8.64%, 7.27%, and 29.37%, with an increase in PV energy conversion efficiency by 2.94%, 2.46%, 2.2% and 6.84% via using air cooling, water back cooling, nanofluid back cooling and waterfront cooling respectively.

Thermal Performance and Optimizing of Composite Trombe Wall with Temperature-Controlled DC Fan in Winter

This paper discusses an improved approach to the Trombe wall: an insulated panel is installed on the inner side, and vents are installed at the top and bottom to connect the outer and inner air layer with the interior. Direct current (DC) fans are installed in the upper vents for stable control of the air circulation. The study first analyzed the thermal performance of this composite Trombe wall, for which the heat load was 27.3% less compared to the classic Trombe wall and 32.1% less compared to the case without the Trombe wall. However, its efficiency for heating the room temperature was not high without heating. Then, we optimized the ventilation efficiency, the proportion of the Trombe wall in the room, and the type of glazing. The highest heat load savings could be achieved when the ventilation openings used high ventilation with temperature-controlled fans and the Trombe wall about 3% of the house floor area. With the use of Low-e double-glazing, we were able to save nearly 41.3% of the heat load than that with the regular single-glazing. For the composite Trombe wall, after taking into account the optimization factors, the room temperature was significantly higher, and could save nearly 52.3% of energy compared to the pre-optimization period.

Trends in best-in-class energy-efficient technologies for room air conditioners

Improving the efficiency of room air conditioners (RACs) could provide significant energy and associated emissions savings, particularly in emerging economies with hot climates where the cooling demand is expected to increase dramatically. To help accelerate efficiency improvements, this study identifies “best-in-class” high-efficiency RAC components and products. The findings show that manufacturers tend to minimize manufacturing costs by using RAC designs that are readily available or standardized to their production, and they share components across various models. High-efficiency RAC models use advanced compressor technologies optimized at a low frequency, large heat exchangers with thermodynamically effective materials and designs, highly efficient direct current fan motors, advanced metering devices, and smart sensors for temperature and humidity control. Recently RAC manufacturers have been improving seasonal efficiency – better reflecting part-load operation – especially via variable-speed (inverter) drives for compressor motors. Recent highest-efficiency RAC models use low global warming potential (GWP) refrigerants, having transitioned from conventional high-GWP refrigerants, in regions where RACs that use these low-GWP refrigerants are commercially available. Recently demonstrated innovative technologies show trends toward smart hybrid designs, evaporative cooling, and solid-state materials beyond the conventional vapor-compression technology. This information could help policymakers improve their RAC market-transformation programs to align with the most-efficient global technology.

Rural Household Space Cooling and Lighting through a Solar Power-based Electric Supply System

Quite a number of households in the world still lack electricity, especially in the sub-Saharan African continent. However, the abundance of solar irradiation in tropical Africa can be advantageously exploited to serve the inhabitants in this region, particularly the extremely low-income earners who not only have access to very inadequate power supply but also experience much discomfort in terms of poor ventilation and heat-triggered infections. This paper focuses on developing a small household-sized solar power-based electric energy supply system together with a temperature control circuit to power a direct current (DC) fan, and a light-regulating circuit to control LED lamps—with additional features such as a digital clock, a remote control, and mobile phone charging units. The system also has a provision for power supply through the mains (whenever it is available). The overall intent is to provide the rural dwellers with a cost-effective way of powering essential devices for basic economic living. This affordable solution is designed, simulated, and constructed to have hardware and software sections supported by various components and devices such as Arduino Mega, Lm35 sensor, RF transceivers, diodes, transistors, regulators, batteries, lamps, a DC fan, etc. The sensor senses room temperature, which is compared with the reference temperature of 25°C programmed on the Arduino microcontroller. When the temperature is less than 25°C, the fan remains stationary but when the temperature is higher than the reference value, the fan begins to run. As the temperature rises further, the speed of the fan increases to maintain adequate ventilation.

A state of the art review of PV‐Trombe wall system: Design and applications

AbstractGlobal energy demand for the future can be met using renewable energy resources, and one of its harvesting tools is the photovoltaic (PV) technology. The combination of solar cell technology and Trombe wall is one of the most important research topics at present. PV‐Trombe walls are receiving great attention because of their applications for simultaneous electricity generation and heating. In this article, a review of available literature covers different designs of a PV‐Trombe wall system besides its thermal and electrical applications. The review covers in detail the influence of design and operational parameters including the glass cover, use of direct current fan, facade width, air vent, air gap thickness, thermal insulation, packing factor, coverage, heat storage, air mass flow rate, PV cell cooling, southern windows, and tilt angle of solar cell on the performance of PV‐Trombe walls. Furthermore, comparison between the PV‐Trombe wall system and classical Trombe wall as well as the applicability of this novel system are revealed. This review article is beneficial to engineers and researchers and can provide information for future studies.

Innovative Low-Cost Sub-Fractional HP BLDC Claw-Pole Machine Design for Fan Applications

As for mass-produced sub-fractional horsepower drives, non-optimal motor behavior (e.g., high cogging torque, output torque ripple, and noise) is often accepted when cost can be reduced, provided reliability is not compromised. This paper proposes an innovative claw-pole motor design for a low-cost single-phase brushless direct current fan drive, improving motor behavior with no increase to the manufacturing cost: 1) reducing cogging torque by proposing unconventional claw-pole skewing and 2) ensuring self-starting capability by implementing air-gap asymmetry. Both measures help reduce the total output torque ripple. The goal is to reduce fan drive noise, especially at low-speed operation, where cogging torque is often the dominating noise source. The design of stator claw skewing and air-gap asymmetry is presented; their effects on motor quantities are studied via simulations and experiments. With the exception of a small reduction of about 1.8% in the back electromotive force fundamental, skewing the stator claws by 30 $^{\circ }$ can reduce the cogging torque by 23% in the simulations and by 28% in the experiments.

Improved Switching Strategy for a Single-Phase Brushless Direct Current Fan Drive and its Impact on Efficiency

Advancing the turn- off angle of the phase current of brushless direct current (BLDC) motors is a common control practice to improve the operating behavior and energy conversion efficiency of such drives by, e.g., reduction of current peaks, copper losses, and breaking torques. This paper investigates a refined switching strategy for a single-phase BLDC motor with bifilar winding to increase the energy conversion efficiency of the system. In addition to advancing the phase current turn- off angle, the turn- on angle is delayed to improve the drive's performance and increase the efficiency even further. This efficiency increase of up to 20.6% is verified experimentally for a speed range from 3000 to 8000 rpm, translating into a reduction of copper losses of up to 37.4% or a decrease of current peaks by 27.4%. The focus is on sub-fractional horsepower single-phase BLDC motors with bifilar winding which, concerning this matter, have not drawn much attention in the literature yet. The findings show that the improved switching strategy can reduce current peaks, breaking torques, copper losses, and therefore increase efficiency over the speed range of interest for fan applications.

Energy analysis of hybrid solar tunnel dryer with PV system and solar collector for drying mint (MenthaViridis)

Abstract This work aims to develop a hybrid portable solar tunnel dryer and enhance its performance using solar photovoltaic system and flat plate solar collector for drying peppermint. The solar tunnel dryer can work in mixed mode (direct and indirect thermal heating). The photovoltaic system is used to operate an axial direct current fan (forced mode). Also, the solar tunnel dryer is provided with a thermal curtain to shade mint and protect it from direct solar radiation. The solar tunnel dryer performance is evaluated by using single, double and three layers of mint, and compared with open sun drying. Predicted and experimental moisture ratio of mint leaves using developed solar tunnel dryer were compared through several models of thin-layer drying. The effect of embodied energy of the developed hybrid solar tunnel dryer on environment was studied. Results indicated that the drying time of peppermint was varied from 210 to 360 min for the developed dryer, while varied from 270 to 420 min for open sun drying. It has been noticed that peppermint drying happened in falling-rate period. The two-term model was the best model to simulate the solar thin layer drying process of peppermint for all treatments. The daily average photovoltaic efficiency was 9.38%, dryer efficiency was 30.71%, overall efficiency was 16.32%, energy payback time was 2.06 years and net carbon dioxide (CO2) mitigation over the lifetime was 31.80 tons. The quality of the dried peppermint by using black thermal curtain in the solar tunnel dryer is higher than that dried in the open sun as the natural color and the appearance are retained more under shading. This system is quite useful for people living in remote areas, where grid connectivity is not available and it can meet the demand of farmers.

Study of a Double-Layer Trombe Wall Assisted by a Temperature-Controlled DC Fan for Heating Seasons

This paper presents a double-layer Trombe wall assisted by a temperature-controlled direct current (DC) fan. THERB for HAM, a dynamic thermal load calculation software, was used to estimate the heating ability of a double-layer Trombe wall for an office building. We designed a new double-layer Trombe wall that has two ventilated air cavities installed on the south facade of the office building, and a pipe with a temperature-controlled DC fan used to control thermo-circulation. The office building was located in Kitakyushu, Fukuoka, Japan. The temperature of the ventilated air cavity of the double-layer Trombe wall and the indoor temperature were simulated. It was more efficient for the DC fan to start when the ventilated air cavity temperature was 19 °C and the operative temperature of indoor was maintained at 20 °C. The results showed that the double-layer Trombe wall with a temperature-controlled DC fan can reduce yearly heating needs by nearly 0.6 kWh/m3 and improve the performance of a double-layer Trombe wall up to 5.6% (22.7% in November, 8.56% in December, 1.04% in January, 3.77% in February, and 3.89% in March), compared to the double-layer Trombe wall without an air supply. The ventilated (all day) double-layer Trombe wall performed better than the unventilated double-layer Trombe wall in November, December, February, and March. Thus, the potential of a double-layer Trombe wall can be improved with the assistance of a temperature-controlled DC fan.

Thermal and Electrical Study for PV Panel With Cooling

<p>Paper presents an investigation on photovoltaic (PV) panel with a direct-current (DC) fan cooling system. The DC fan cooling system was installed at the back of PV panel in order to reduce its operating temperature. The performance of PV panel can be affected with the increase of its operating temperature. Therefore, with the aid of the DC fan cooling system, it can enhance the performance by raise the output power generated. However, DC fan cooling system is considered as an active cooling system, whereby it consumes input power in operating it. The thermal behavior of PV panel with different DC fan speeds were observed by using a computational fluid dynamic (CFD) software. From the temperature obtained, a current-Voltage (I-V) and power-voltage (P-V) can be formed by using PSPICE due to examine its electrical performance. As the DC fan speed increases, the power input to operate it also increase. Hence, it is crucial to find the optimum speed so that the power generated by PV panel that can be saved is high.</p>

Temperature Distribution of Three-Dimensional Photovoltaic Panel by Using Finite Element Simulation

The low electricity performance of a photovoltaic (PV) panel has been concerned in the PV application system. The effect of environmental and operating condition was affected the performance of the PV panel. In this research work, the main objective is to perform a three-dimensional geometry model of monocrystalline silicon PV panel with and without cooling system by using finite element method. In the case of a cooling system, the effect of the Direct Current (DC) fan flow rate on the temperature distribution of PV panel was investigated. The electrical behaviour of this PV panel is obtained based on the average temperature of the PV panel obtained and average solar irradiance from site location. According to the experimental results, PV panel with cooling system can be significant to provide better performance than the PV panel without cooling system in the same environmental condition. For the effect of flow rate of DC fan in the PV panel with cooling system, the performance of this PV panel has been improved as increasing in flow rate of DC fan.

Cooling efficiency of a brushless direct current stand fan

In warm environments, isothermal cooling by deliberately enhanced air movement can maintain thermal comfort using less energy than compressor-based air conditioning. To evaluate the performance of a brushless direct current (DC) stand fan, the cooling fan efficiency (CFE) index was measured in a climatic chamber under four dry-bulb temperatures (24, 26, 28, and 30 °C), six speed settings (corresponding to centreline speeds in the range 0.6–2.5 m/s at 1 m distance), two fan-manikin distances (1 and 2 m) and two orientations (front, side). The CFE index is defined as the ratio of the whole-body cooling effect generated by non-uniform airflow from the fan to its power consumption (°C/W). The CFE index overcomes the limitations of assessing the cooling effect based just on a few air speed measurements. The results show that the CFE index is influenced by dry-bulb temperature, fan speed setting, and fan-manikin distance, but not by fan-manikin orientation. The lower the temperature and the closer the fan, the higher is the CFE index. Increasing fan speed setting simultaneously enhances whole-body cooling and increases power use. Consequently, the CFE has a non-monotonic relationship with fan speed setting and the peak value is reached for an intermediate speed. As compared with previous testing results using an alternating current stand fan, the CFE index of the DC fan we tested is three times higher. As a complement to air-conditioning, the tested stand fan is a suitable energy-efficient technology for providing thermal comfort in warm environments.

20716 小型直流ファンの振動特性(一般講演 振動・音響)

The subject of this research is three kinds of small direct current fan. The causes of the vibration under operation in a small direct current fan are an unbalance and a pressure fluctuation. The vibration is a big problem in the use environment of a small direct current fan, and the vibration reduction of a small direct current fan and the evasion of the resonance are requires. hi this paper, the vibration phenomenon of a small direct current fan was analyzed while operating, and the spectrogram of the object was obtained. The phenomenon was understood by the Experimental Modal Analysis.

System, method, and computer-readable medium for reduction of commutation-related acoustic noise in a fan system

A method for reducing commutation-related acoustic noise in a fan system is provided. A constant frequency periodic signal is generated and a fan commutation event is synchronized with a zero level value of the constant frequency periodic signal. A system for controlling a direct current fan is provided. The system comprises a signal generator adapted to produce a periodic signal of a constant frequency and a phase-locked loop. A zero level value of the periodic signal is synchronized with a commutation event of the fan.