Mohammad Sameti

Optimisation of a combined Stirling cycle–organic Rankine cycle using a genetic algorithm

In a Stirling cycle a huge amount of energy is wasted due to the losses. This wasted energy may be utilised as a heat source for the boiler of an organic Rankine cycle (ORC). Combination of these two cycles leads to an increased cycle efficiency compared to a single Stirling cycle and the analysis and optimisation of the integrated system is carried out. Optimisation is performed using the genetic algorithm and considering three decision variables: the temperature of the cold tank of the Stirling cycle, the pressure ratio and the temperature of the ORC condenser. In optimisation, the efficiency is considered as the objective function and the highest value is achieved by adjusting the decision variables. Using this method, the efficiency of the overall combined cycle was improved in which the highest efficiency was obtained to be 41.5%.

Prediction of solar Stirling power generation in smart grid by GA-ANN model

A model based on the feed-forward Artificial Neural Network (ANN) optimised by the Genetic Algorithm (GA) is developed in order to estimate the power of a solar Stirling heat engine in a smart grid. Genetic Algorithm is used to decide the initial weights of the neural network. The GA-ANN model is applied to predict the power of the solar Stirling heat engine from a data set reported in literature. The performance of the GA-ANN model is compared with numerical data. The results demonstrate the effectiveness of the GA-ANN model.

Numerical simulation of solar-driven Kalina cycle performance for centralized residential buildings in Iran

ABSTRACT The building sector is responsible for most of the worldwide electrical energy consumption, having surpassed both the industry and transportation sectors. In this article, a detailed thermodynamic model was proposed for a solar-driven Kalina cycle with an auxiliary superheater to meet the electrical demands of high-rise buildings in Iran’s climatic condition. A combination of correlations characterizing the Gibbs free energy of an ammonia–water mixture was utilized to describe the behaviour of the working fluid. Then an energy analysis of the cycle was studied to solve the system state points as well as the system performance. So its maximum monthly power generation is estimated. A long-term balance is considered between the electricity production and consumption for residential sectors based on the available 10-year recent data for 113 suitable sites. The energy consumption of residential buildings in each province is averaged to calculate the energy consumption of a typical building in that province. Then, the results were shown in terms of solar electrical coverage for each site. The Kalina solar system was able to cover the annual electricity demand of a residential building of at least 20.34% for Hormozgan and at most 164.36% for Isfahan.

Numerical modelling and optimization of the finite-length overhang for passive solar space heating

ABSTRACT Overhangs are usually used with direct gain solar heating to reduce gains during times when heat is not wanted in the building. As these energy-saving devices may partially shade absorbing surfaces during periods when collection is desired, analysis of their effect on the absorbed radiation is necessary. In this article, a detailed mathematical model was developed to simulate the solar thermal energy transfer through a window with finite overhang. The effects of the finite overhang on the solar energy components (i.e. beam and diffuse) received by the aperture is considered in detail for various shadow patterns. A simulation was carried out to analyse the energy saving. In the practical applications, the use of these shading devices in the building can be beneficial at certain times of the year; however, they are counter-productive at some other times. Therefore, a multi-objective optimization was needed for optimal sizing to maximize the total annual energy saving through the building during cold and hot periods. The modified solar radiation synthetic energy-savings coefficient objective function was used to calculate optimal shading.

Thermodynamic study and performance simulation of a renewable-based Kalina cycle in distributed generation

Abstract A major advance in affordability of solar electricity may occur with Kalina solar system which offers a path to provide an efficient heat-to-electricity. In this study, a comprehensive thermodynamic model is introduced to simulate a Kalina cycle which exploits solar thermal energy as the source to be used in distributed generation. Ammonia–water mixture was considered as the working fluid where its thermos-physical behavior was modeled using detailed correlation in the cycle. A case study is performed for different cities of Iran to evaluate the potential of the proposed system for supplying electricity for residential sector. The results showed that in some sites, the production exceeds the demands for almost 25%.