نشریه مهندسی مکانیک تبدیل انرژی
سال نهم شماره 4 (پیاپی 33، زمستان 1401)

In this research, with the help of thermodynamic modeling of an XU7 engine (manufactured by Irankhodro Co.), the effect of insulation and modification of the intake air route (IAR), in a real hot and humid weather case study(49 ° C and 20.2% relative humidity similar to a normal summer day of Khuzestan state climate) is investigated. In this regard, assuming hot engine run-up and naturally aspiration condition, the thermodynamic model of the processes of a spark ignition engine, based on the Anand combustion model, was developed. In the process of modeling the irreversible work of viscous friction caused by lubrication of pistons and rings, assuming the constant viscosity of the lubricant as well as two compression rings for each piston, was considered. The physical effects of the presence of moisture in the engine intake air(EIA) were taken into account. Considering two different cases, the effect of heat transfer to EIA was applied. Case 1: gradual heat transfer approach along IAR and case 2: heated air suction approach before entering IAR (This approach is closer to reality). The cylinder body temperature as well as the equivalence ratio in the combustion process are considered constant at all crank angular velocities. The results were verified by reputable authorities. The results showed that reducing the EIA temperature due to the insulating IAR is effective for each of the above two cases. But in the second case, this action has a greater impact. Based on the results, the effect of insulating IAR of the XU7 engine in the mentioned weather conditions can be simultaneously, Leads to a 12% increase in engine output power (at 6000 rpm) and also a 10.3% increase in engine output torque (at 1000 rpm).

This paper presents a new, low-cost, and unsophisticated method to increase the thermal power of conventional baseboard radiator systems. A new design was achieved by separating the go and return paths of the fluid and eliminating the conductive thermal bridge between them. The experimental tests as per the National Iranian INSO 360-2 standard revealed the expected improvement in thermal power. The comparison of the new design’s thermal power with that of the conventional methods in the industry shows 72% and 42% increases versus the two designs reviewed in the authors’ previous works. This research showed that higher thermal power could be accomplished with no need to increase the feeding temperature, the height of the baseboard profile, and the flow rate of the working fluid, which would result in saving in energy consumption and increasing the capability of coping with cold weather and providing more thermal comfort for residents. This thermal power enhancement will be more important when there are constraints on increasing the length of baseboard radiating systems inside the home space.

In this article, according to the meteorological information and the data obtained from the meteorological maps, the selection of equipment and air conditioning system of a 5-story building in the city of Tehran is investigated, and the cooling and heating loads are calculated according to the geographical location of this building. The heating and cooling of the living room has been done to select the radiator for each room and the first part of this article has been calculated manually, and the second part has been used to verify the results of the loads using Carrier software, which is an important software in the field of air conditioning. Surface cooling is done

Possessing enormous potential, Iran can significantly expand solar photovoltaic energies. Thus, it is so consequential to accurately estimate investment costs according to the climate and geography of Iran. We conducted an economic analysis regarding adjustment factor in guaranteed purchase of renewable electricity based on the recent enactment of the Power Ministry respecting guaranteed purchase of guaranteed solar electricity. Then we evaluated the investment costs of grid-tied photovoltaic solar energies in the centers of provinces of Iran applying RETScreen as well as economically examining the amount of aggregate incomes, the reduction in the amount of carbon emission on an annual basis and net profit income through 20-year lifetime of solar power station for each center of provinces. It is the most qualified to install solar power stations in the six top ranking cities, otherwise it will be economically unjustifiable. Considering minimum prices of economically justifiable guaranteed electricity through 20 years has been suggested to SATBA (The Organization of Renewable Energies and Energy Efficiency). Also, the maximum bank loan interest rates have been estimated to determine that running these projects would be economically justifiable for all these cities.

Coasts and harbors can be considered huge sources of energy, which can be seen in the form of waves, tides and constant surface or underwater currents, due to the temperature difference between different points. Energy production in this way does not involve pollution. These power plants can generate energy throughout the year. In this study, finite element method has been used to model the generator as one of the most accurate simulation methods for the desired calculations, which can be used on shores, ports and ship hulls, and the oscillating movements of water waves can be easily converted into energy. Lightning. In this paper, the mechanism of this type of generator is modeled and simulated. The simulation results showed that the implementation and construction of these generators have good efficiency and high economic efficiency. Reliable simulation tools are essential for studying the performance and viability of wave energy devices, as experiments are both costly and difficult. In particular, the ability to survive in nonlinear waves is one of the biggest challenges to wave energy, and since waveforms and dynamics are highly dependent on the model, each device must be studied separately with approved instruments. To take. In this study, the design of the generator including rotor, stator and wiring will be fully investigated. For this purpose, first the mathematical relations related to the generator are stated and at the end, the analytical design of a generator example will be examined. In this study, the finite element method has been used as one of the most accurate simulation methods for the calculations.

The development of residential complexes and the increase in the height of buildings and the increase in the cost of energy carriers and the need to save energy have caused the introduction of new and dangerous ideas and technologies along with flammable materials and increase the fire load in the building. Deliberate and indeliberately fires recent years, It shows the shortcomings of the measures foreseen in the design of these complexes in providing the security of the residents and protecting their property and business. This research intends to provide reliable solutions to reduce the vulnerability in the above challenge by using the principles and criteria of architecture and with the help of experts' opinions. The research method in this research is a combination of qualitative and quantitative methods which was done by Delphi method. The results were analyzed in SPSS 26 software and with the help of KMO and Bartlett test, the adequacy of the sample size has been confirmed. With the help of Q factor analysis, the results have been extracted and the most influential factors on reducing vulnerability to fire in high-rise residential buildings have been determined. Based on the results of the research, the factors influencing the reduction of the building's vulnerability to fire are: Accessibility, drainability, materials, separation of the building, form, space, elements and elements that spread fire and smoke, form, space, elements and elements that block and divert fire, smoke and toxic gases.