faramarz talati

The growing trend of human society's need for energy consumption and the problems in energy production, leads to paying attention of researchers to recycle and improve the quality of waste heat sources. In this regard, an absorption heat transformer is one of the most attractive energy-saving technologies. Also, the loop heat pipe is a simple device that is able to transfer heat over long distances.Using the loop heat pipe as heat exchangers inside the absorption heat transformer system can lead to improving its performance. Therefore, it is necessary and important to assess the feasibility and effect of using the loop heat pipe in the absorption heat transformer system. In this study, at first, both of the mentioned systems were analyzed and validated separately from the thermodynamic point of view. Then, the thermodynamic analysis of the absorption heat transformer system integrated with the loop heat pipe was done and its performance was compared with the conventional absorption heat transformer cycle. All investigations are done in the EES software and the working fluid of the cycle is LiBr-H2O. The results show that the COP and ECOP of the combined cycle are higher than the conventional absorption heat transformer cycle.

In this paper, the annual and economic performance of an integrated solar combined cycle (ISCC) with indirect energy storage tanks is investigated. The study includes four scenarios, in which the combined cycle performance was studied exclusively in the first scenario. In the second scenario, the integrated solar combined cycle (ISCC) was examined, and the use of supplementary firing instead of solar energy with the assumption of producing the same power as that by the ISCC scenario was examined for the third scenario. For the fourth scenario, the use of energy storage in the form of indirect tanks with the purpose of energy storage during peak solar direct normal irradiation times and discharge during peak power electricity consumption within the network for such power plants were subjected to investigation. Results show that the contribution of solar energy in the annual produced power by the ISCC scenario is 40 GWh, which is 2.2% of the total. In the case that this amount of power is produced using supplementary firing, there will be about 1.98 tons of increased fuel consumption, and about 18 kton increased in CO2 production. By using the energy storage system, the annual power generation increases by 5 GWh, which will raise the plant's annual revenue by 0.25 M$ if the increment occurs during peak hours.  Moreover, the levelized costs of energy (LCOE) for the four scenarios are 8.99, 8.86, 9.04, and 9.135 cents/kWh, respectively.

Hyperthermia is one of the first applications of nanotechnology in medicine by using micro/nano magnetic particles that act based on the heat of ferric oxide nanoparticles or quantum dots in an external alternating magnetic field. In this study, a two-dimensional model of body and tumor tissues embedded is considered. Initially, the temperature distribution is obtained with respect to tumor properties and without the presence of an electromagnetic field. Then, the effect of the electromagnetic field on the temperature distribution is studied. The results are compared with those of other papers. The results indicate that the use of the electromagnetic field causes a significant rise in the tumor temperature; however, the risk of damage to the healthy tissues surrounding the cancerous tissue seems to be high. Then, the micro/nanoparticles are injected into the tumor tissue to focus energy on cancerous tissue and maximally transfer the heat onto the tissue. The temperature distribution in the state is compared with the case with no nanoparticles and other numerical works. The results demonstrate that with the injection of nanoparticles into the tumor, the maximum temperature location is transferred to the center of the tumor and also increases to 6°C. After determining the temperature distribution in the presence of nanoparticles, the effects of different variables of the problem are studied. According to the obtained results, the increase in the concentration and radius of nanoparticles have a positive effect on the temperature distribution in the tissue; on the other hand, the increase in the frequency and size of the electrodes have a negative effect. The relevant equations are solved numerically using the finite difference method.

An integrated solar combined cycle (ISCC) is analyzed at "off-design" operating conditions. Using the principles of thermodynamics heat and mass transfer a computer code is developed in FORTRAN programming language to simulate the system’s hourly performance under steady state conditions. Three scenarios are considered for the study. In the first one, only the combined cycle (CC) is studied. In the second scenario, two solar heat exchangers are added to the system (ISCC) to produce some extra steam fed to the steam turbine for more power production. In the third one, as that of the ISCC scenario, a supplementary firing is used instead of solar heat exchangers to produce the same power. The main performance parameters are calculated for the hourly variation of solar direct normal irradiation intensity (DNI) and ambient air temperature for analyzing environmental benefits of using solar energy instead of supplementary firing. Results show that the contribution of solar energy in the annual produced power by the ISCC scenario is 75.14 GWh, which is 2.1% of the whole. In addition, it is found that using solar energy leads to an annual reduction of 36.13 Kton in the produced CO2 and an annual fuel saving of 3.76 ton.

The use of phase-change material to enhance the capacity of energy storage/release is the subject of many new researches on management of the energy supply. Study of these systems is directly related to the solid-liquid phase-change problem, in which the evaluation of temperature distribution, position of phase-change front and liquid or solid fraction becomes a basic problem. Study of freezing and melting process with regard to natural convection in the liquid phase is the main purpose of the present paper. For this purpose, a rectangular finned container of phase-change material is intended. Fins are used to enhance the heat transfer rate. This fact necessitates the use of immersed boundary condition on the solid phase. Hence, the melting process considering the both effects of natural convection and movement of solid phase is studied. The freezing process is also studied taking into accounts the natural convection with no need to impose the immersed boundary condition. Lattice Boltzmann method is used as a numerical method and results are reported based on the dimensionless parameters. Based on the results, the effects of natural convection is negligible during freezing process, while imposing the effects of natural convection provides a significant change in the required time for complete melting of the phase change material.