Iranica Journal of Energy & Environment
Volume:13 Issue: 4, Autumn 2022

Most of the spaces in contemporary houses in Iran cannot achieve enough daylight during daytime. Daylight utilization has a significant impact on decreasing energy consumption in residential buildings. Residents are deprived of natural daylight when there is no attention to the design based on daylight. Iranian traditional architects use practical and straightforward methods in constructing courtyards houses to provide comfort conditions in unique rooms in courtyard houses in terms of daylight quality. In this research, the daylight quality of five separate rooms around the courtyard of Yazdanpanah's house was investigated through an experimental method. Average work plane illuminance and uniformity ratio were calculated in these rooms of the house in Kerman city, located in Iran's hot and dry climate. Findings of this research demonstrated that all rooms surrounding the courtyard of traditional houses have the ability to achieve work plane illuminance of more than acceptable value. Among all rooms around the central courtyard, one room facing the south direction achieves more than 500 Lux work plane illuminance. The amount of uniformity in this room is acceptable with more than 0.5 on most of the days in a year. The findings of this research could be used to design more comfortable rooms in contemporary houses in terms of daylight quality by creating central courtyards.

Renewable energy is energy that can be used indefinitely. As a result, renewable energy sources such as solar photovoltaics developed. Conventional converters, typically used to connect the microgrid to the battery, only change the voltage. To link the microgrid to the battery, bidirectional converters are required. A bidirectional converter is available in a variety of configurations. The control structure is highly sophisticated to obtain a satisfactory output. This article proposes a bidirectional DC-DC buck-boost converter for controlling current in DC microgrids, solar systems, and loads. A bidirectional DC-DC Buck-Boost converter is required to transmit and receive energy from the battery to the DC microgrid. When voltage is sent to the DC microgrid, the battery voltage is reduced. Otherwise, the charging voltage is increased when a battery is charged by voltage. This converter produces a better output voltage than an AC-DC Buck-Boost Converter, and its switching frequency is double that of typical converters. The modified DC-DC converter has the simplest form and the advantage of having the highest responsiveness.

Numbers of waste concrete have generated from construction and demolition waste (CDW) threaten environmental and human health due to the illegal dumping practices in several countries. Recently, the recycling of waste concrete has demonstrated the ability to reduce dependency on a natural resource in producing building materials as well as reducing carbon footprint in the concrete manufacturing process. The objective is to determine the limitation factors of Waste Concrete Aggregate (WCA) as a replacement for virgin concrete aggregate. Analysis by X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF), leaching, and sulphate tests were used to identify the physicochemical characteristics of WGA. Results showed WCA has high water absorption, expansion of Alkali-Silicate Reaction (ASR), low adhesive strength between aggregate and cement, leachability, and high soluble sulphate. CaO, Al2O3, SiO2, SO42-, Cr2O3, SrO, and Al2O3 were the main chemical components consisting of WCA. The leachability of Ca, Zn, and Cr in WCA was pH-dependent. High soluble sulphate content in WCA determined the extension formation of micro-crack in WCA due to extensively recrystallizing the Delay Ettringite Formation (DEF) in WCA.  The formation of micro-crack, ASR, and low adhesive strength between aggregate and cement insides of WCA significantly affect the durability of recycled products in building structures. High water absorption and leachability of WCA enhanced the release of heavy metals in soil. Therefore, these limiting factors in WCA were necessarily treated before being utilized as a part of the recycled product.

This numerical and experimental work aims to improve the heat transfer inside a solar thermal collector. By incorporating rectangular baffles in the middle of the distributed air passing channel at different angles of inclination (ß= 90°, ß= 180°, ß= 180° and ß= 90°). That is called the model H. These experiments were carried out in the Biskra region of Algeria in good natural conditions with an average solar radiation approximately constant I= 869 W/m2 varying from 11:30 to 14:00. After the completion of the experimental investigation, a computational fluid dynamics (CFD) model was created that matches this experimental model with the same experimental boundary conditions. In the numerical study, ANSYS Fluent 18.1 was used to conduct simulations and compare the results of the thermal and hydraulic performance of the collector. It was concluded that the effectiveness of the CFD model, meaning that the theoretical and numerical data were very close to each other for all mass flow rates. As the mass flow increased the heat transfer process increased, while the absorber plate temperature inside the collector for experimental and numerical studies decreased. Addition of baffles increased heat transfer, due to the creation of turbulent flow that leads to crack the dead thermal layers near the absorber plate, which leads to an increase in heat transfer from the absorber plate to the air.

The rising cost of concrete production due to the global recession in world economy caused by the COVID-19 pandemic and the greenhouse gases emitted in the production of cement has necessitated the need for alternative materials for cement. In this study, bamboo strips and steel rebars were used as reinforcements in a ternary blended concrete to determine their strength properties. In alignment with standard requirements for testing, concrete specimens were tested at curing ages of 7, 14 and 28 days for compressive, splitting tensile and flexural strengths. The morphological and bond characteristics of the bamboo were determined through the Scanning Electron Microscopy (SEM) and Fourier Transform Infra-Red Spectroscopy (FTIR), respectively; while its tensile strength was determined and compared with that of steel reinforcement. These results showed that bamboo is ductile and has stretching vibrational spectrum. The combinations of quarry dust, river sand, Rice Husk Ash (RHA) and Guinea Corn Husk Ash (GCHA) yielded compressive and split tensile strengths of 20.4 N/mm2 and 2.18 N/mm2, respectively. Concrete with 50 % river sand and 50 % quarry dust performed better in flexure for both Bamboo Reinforced Concrete (BRC) and Steel Reinforced Concrete (SRC) at 28 days with strengths of 12.75 N/mm2 and 22.49 N/mm2, respectively. Therefore, bamboo, quarry dust, rice husk and guinea corn husk ash can be used for reinforced concrete production.

Soil polluted with urban wastewater due to defect of wastewater disposal and leakage from wastewater channels is a common type of pollution in urban areas which in addition to environmental damage, has significant effects on soil engineering parameters. In present study, effects of municipal wastewater on mechanical behavior of soil and clay microstructure was studied, and then effects of iron oxide nanoparticles on remediation trend of contaminated soil was investigated. To achieve this, unconfined compressive strength (UCS), collapse and SEM analysis tests were performed on contaminated samples containing 20%, 60% and 100% wastewater at 1, 3 and 5 months and also on contaminated soil remidiated with 0.5-4% Iron nano oxide. Results showed that wastewater reduces shear strength of clay and this decreasing trend increases with increasing percentage and contamination duration. UCS of soil contaminated with 100% wastewater decreased by 49% after 5 months of contamination. Also, wastewater in the soil caused to soil collapse after 5 months . SEM images showed the clay structure became clotted after contamination and soil pores increased compared to natural soil.  Improvement phase results showed that by addition of Iron nano oxide to contaminated soil, shear strength significantly increased, and optimal percentage of Iron nano oxide was 3% in which UCS increased by 105.2%. By increasing the percentage of Iron nanoxide, intensity of collapse index of contaminated soil decreases. Best case senario, final strain of soil decreases by 43.4% compared to contaminated soil. Therefore, utilizing Iron nanooxide is recommended to improve engineering behavior of contaminated clay.

For decreasing the fuel consumption of internal combustion engines, and also reducing the emissions, investigation of the effective parameters on power, emissions, and the combustion phasing is important. In this study, the influence of adding water to a Reactivity Controlled Compression Ignition (RCCI) engine has been numerically investigated. For this purpose, water with different mass fractions was added to the air-fuel mixture. In order to simulate the engine, AVL Fire software was used. The results show that substituting a portion of gasoline fuel with water, up to 10% mass fraction, raises the combustion chamber pressure. In this condition, the production of hydroxyl free radicals, as one of the characteristics for the start of combustion, occurs earlier. Furthermore, Indicated Mean Effective Pressure (IMEP) remains unchanged. By further increasing the water mass the production of hydroxyl radical decreases, and the high-temperature heat release is delayed; also comparing to when water was not added, average temperature of the combustion chamber reduces, while the amount of CO production does not change. Increasing the number of water moles increases the maximum in-cylinder pressures so that compared to pure gasoline mode, by replacing 20% of gasoline mass with water, the indicated mean effective pressure approximately stays the same.

The phenomenon of nuclear boiling has always been recognized suitable for heat transfer between different boiling regimes. Study on boiling is considered as a new field which meets different research and industrial needs such as heat transfer in nuclear reactors, cooling units, rocket motors, electronic equipment cooling, batteries, etc. In this study, a chamber with immiscible fluid, water, steam, and air, having a side wall with uniform heat flux has been studied in 3D. To do so, we first considered the prediction of the heat flux interval for which the boiling occurs in the form of nuclear boiling. In this study, two-phase fluid volume (VOF) approach was used for modelling boiling on the vertical wall and two-phase flow. In this research, Ansys software package was used for numerical modelling and numerical simulation. Distribution of the velocity field follows more uniform pattern in dimensionless heights less than 0.9. In this study, bubbles are only present near a wall with heat flux that has a lower Rayleigh number. Also, existence of these bubbles on the wall, which prevents fluid infiltration, affects vortices caused by natural convection. However, the general and uniform patterns of vortices remain unchanged in most part of the fluid, which is because of the limited amount of bubbles near the wall with heat flux. Natural convection increases the height of fluid inside the chamber, which leads to the formation of stronger vortices at a dimensionless height of 0.9 that has a high Raleigh number due to high heat flux. In this case, the continuous use of heat flux gives rise to the production of bubbles over time.

The development of models that predict power production of wind farms (WFs) by considering the interacting wakes is important; because wakes of the turbines exert a significant influence on power production of turbines, and hence on the layout of wind turbines in WFs. Thus, the purpose of present study was to provide an innovative analytical method for the prediction of power generation of the WFs that have a flat terrain and are consisted of horizontal-axis wind turbines (HAWTs) with the same hub height. The methodology employed utilized an analytical Gaussian model of HAWT wake to develop an analytical model that calculates the effective wind velocity acting on the downstream HAWT(s), which is further used for reading its generated power from the turbine’s catalog; thus, providing the generated power of the WF as the output. The results of presented model were validated by the field measurements data of Horns Rev WF and also were compared to two analytical models for predicting the generated power. The results were compared with two numerical simulations of the literature, and the output data of three commercial software. Moreover, the error analysis revealed that the presented model mostly showed superior accuracy in predicting the field measurements data.

Biomass use in small unit combustion systems such as for space heating or cooking could lead to ineffective mixing and potential problems arising from emissions of gaseous and particulate pollutants. We therefore conducted a study to measure pollution levels in public kitchens using biomass fuel for cooking and to ascertain their air quality indices. Markers of indoor air quality such as CO, SO2, H2S, PM2.5 and PM10 were measured in eleven (11) public kitchens of selected secondary schools over a period of four months by a set of active sampling devices. It is revealed that the mean average of CO, SO2, H2S, PM2.5 and PM10 sampled in the indoor microenvironments of the selected kitchens are 46.29 ppm, 0.36 ppm, 0.28 ppm, 74 µg/m3 and 138 µg/m3, respectively. The AQI assessed for CO for the kitchens was 36.36% very hazardous, 54.54 % hazardous and 9.09% very unhealthy while 63.64% and 36.36 % of very unhealthy and unhealthy categories, respectively for SO2. This shows that the indoor air pollution levels in selected kitchen are elevated and results in potential negative health consequences.

The aim of present study was to investigate the relationship between hydraulic and ecological variables of the studied span and to investigate changes in living conditions of phytoplankton (Amphora ovsalis and Navicula placentula). According to the measurements and analysis of habitat fit curves, it can be concluded that the highest frequency of Amphora ovsalis and Navicula placentula occurred and specified at flow rate of 15.82 and 14.942 m3/s, respectively. As can be seen, the lowest frequency of Amphora ovsalis and Navicula placentula in this measurement occurred at flow rate of 15.355 and 5.289 m3/s, respectively. The best habitat conditions for Amphora ovsalis and Navicula placentula are in the range of 0.18 -0.31 and 0.18 - 0.265 of Froude number range respectively. The highest density and abundance of Amphora ovsalis and Navicula placentula was observed in the range of 0.017 - 0.055 and 0.017 -0.039 mg/l of phosphate demonstrating that the best growth and living conditions are predisposed in this range for these species had suitable habitat conditions for life in this range. The highest frequency of Amphora ovsalis and Navicula placentula is in the range of 0.019 - 0.071 and 0.047-0.071 mg/l nitrite, respectively. Amphora ovsalis and Navicula placentula had the highest frequency when nitrate ranges 4.48 – 5.16 and 4.48- 5.37 mg/l. The best habitat conditions for Amphora ovsalis and Navicula placentula were between the mean velocity values in the range of 1 -1.2 m/s.

In this study, the simultaneous effect of suction and blowing on the boundary layer and the effect of control parameters on the flow separation from a NACA 0012 airfoil is numerically analyzed. Reynolds number is considered 500000 , and the shear stress transport (SST) k-w turbulence model is used to estimate eddy viscosity. The airfoil is supposed to be 2-D. To validate the numerical results, they were compared with reported experiments. In the flow control by simultaneous suction and blowing, the location of the suction jet was 0.1 of the airfoil chord from the fixed leading edge, and that of the blowing jet was 0.5, 0.7, and 0.9 of the airfoil chord from the leading edge. When the blowing location is at 0.5 of the airfoil chord, better results are observed than I n; other locations. An increase in suction jet velocity increases the lift-drag ratio between 22% and 55%. Also, increasing the blowing jet velocity increases this ratio between 43% and 55%. Horizontal blowing has the most negligible effect on improving aerodynamic characteristics. Based on the results, at the angle of attack of 16°, blowing is most effective in the flow control at  with an approximate velocity of half the free stream velocity. In this condition, vertical suction has the best effect , and the lift-drag  ratio will increase by 76%.