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This article introduces a novel multiple-cycle generation system for efficient heat recovery at high and low temperatures. The system is modeled and optimized using the M2EP analysis method (mass, energy, exergy, and performance) and the particle swarm optimization algorithm. The multigeneration system produces electricity, cold, domestic hot water, and biogas by utilizing Kalina cycles, diffusion–absorption refrigeration machines, and high-performance heat exchangers by harnessing waste heat from cement kiln exhaust gases. The Kalina cycle is employed for electricity generation, wherein the H2O+NH3 mixture, heated by hot water, circulates through heat exchangers. Downstream of the Kalina cycle, the refrigeration machine generates cold by evaporating the strong solution of the H2O+NH3 mixture. Hydrogen circulates in the diffusion–absorption refrigerator (DAR) circuit, facilitating the exchange between the evaporator and the absorber. The domestic hot water and biogas production systems operate at lower temperatures (around 45 °C). The simulation results for the Kalina cycle indicate an electrical energy production of 2565.03 kW, with a release of usable energy (residual gases) estimated at 7368.20 kW and a thermal efficiency of 22.15%. Exergy destruction is highest at heat exchanger 1, accounting for 26% of the total. A coefficient of performance of 0.268 and an evaporator temperature of 10.57 °C were obtained for the DAR cycle. The absorber contributes the most to energy exchanges, comprising 37% of the entire circuit. Summarizing the potential for valorizing waste heat from cement kilns, this article lays the foundation for future research.

The global concern regarding the environmental repercussions of refrigerants has escalated due to their adverse effects. These substances deplete the ozone layer and intensify the greenhouse effect. International agreements such as the Montreal and Kyoto Protocols and COP21 have imposed restrictions on refrigerants with high global warming potential (GWP) to address these issues. This study aims to explore the feasibility, energy efficiency, and environmental impact of utilizing the HFO (hydrofluoric-olefin) refrigerant R1234ze as a substitute for HFCs (hydrofluoric-carbon) (R134a, R407C, and R410A) and HCFCs (R22) in air-cooled vapor compression refrigeration and air conditioning systems. To determine their effectiveness, we evaluate the energy performance of various refrigerant operating cycles across a wide range of ambient and evaporating temperatures. Additionally, we conduct environmental impact analyses based on the total equivalent warming impact (TEWI) parameter calculated for commercially available chillers that utilize the fluids mentioned above. Our findings indicate that vapor compression chilled water systems employing R1234ze exhibit the highest performance coefficient and the lowest annual TEWI.

The energy transition, originating in the limitation of fossil resources and greenhouse gas (GHG) emission reduction, is the basis of many studies on renewable energies in different industrial applications. The diffusion absorption refrigeration machines are very promising insofar as they allow the use of renewable resources (solar, geothermal, waste gas, etc.). This technology is often considered an alternative to vapor compression systems in cooling and refrigeration applications. This paper aims to overview the thermal mechanisms related to modeling system energy sources and highlight the primary methodologies and techniques used. We study and analyze the technology’s current challenges and future directions and, finally, identify the gaps in the existing models to pave the way for future research. The paper also gives a classification of absorption refrigeration systems (ARS) to position and limit the scope of the study. The paper will help researchers who approach the various aspects to have a global synthetic analysis of the mechanisms characterizing the modeling of energy sources of absorption refrigeration machines.

This article presents the numerical modeling of the thermochemical conversion of biomass and tires as alternative fuels in kilns dedicated to the production of cement. The study seeks to understand and control the phenomena that occur when heavy fuel oil (traditional fuel) is partially replaced by biomass and tires. These are thoroughly mixed with meal at the entrance to the rotary kiln and form the bed of solids. The mathematical model developed takes into account both chemical reactions of meal and alternative fuels. At the entrance, the meal is made up of species such as CaCO3, MgCO3, Al2O3, SiO2, Fe2O3, MgO, CaO, C2S, C3A, C4AF and C3S, some of which form along the kiln. The article focuses specifically on the influence of alternative fuels on the clinker or cement obtained. The properties (moisture, organic matter, composition, energy value, etc.) of the biomass and the tires, which are associated with the operating parameters of the kiln, greatly influence the production of clinker. In order to understand and control the behavior of each material and the operating parameters in the clinker (cement) production process, the mathematical model follows the evolution of each species and parameters step-by-step, until the clinker is obtained. The effect of alternative fuels on clinker production was found for the kiln’s operational parameters, the dynamic angle of the bed (30°), the angle of inclination of the kiln (2°), rotation (2 rpm), the length and the inside diameter, respectively (80 m) and (4 m); the chemical and physical properties (humidity, organic, inorganic matter, C, H, O, N, S, Cl); the lower calorific value, raw material); and the numerical parameters (spatial discretization 30 and 120). Despite the high energy content of tire fuels, the results of the use of biomass give better characteristics of clinker/cement (52.36% C3S and 3.83% CaO).The results found show that biomass pyrolysis is endothermic, with the heat of reaction found to be ∆rHpyro=184.9 kJ/kg, whereas for tires, a heat of reaction of ∆rHpyro=−1296.3 kJ/kg was found, showing that the pyrolysis of this material is exothermic. Char production is higher in the case of tires than in the case of biomass, with rates of 0.261 kg/kgOrg.Mat. and 0.196 kg/kgOrg.Mat., respectively. In both cases, waste conversion was complete (100%). The cement obtained in the different cases meets the requirements of Portland cements (73.06% silicates and 18.76% aluminates), the conversion of alternative fuels is complete (100%), and the specific energy consumption is almost consistent with values from the literature.

The dwindling and scarcity of fossil energy sources is the basis of the energy transition, where renewable resources are increasingly valued. The purpose of the cogeneration system studied in this article is to recover the residual heat from the gases coming out of the chimneys of the cement kilns, to produce at the same time the electricity and the heat required for offices and residential houses of cement workers. Cement kilns are reputed to be energy-intensive, generating excessive heat losses. These heat losses are found mainly in the conduction–convective and radiative modes, representing about 26% of the overall heat input to the system. Nevertheless, the gases at the chimney outlet can still have temperatures between 250 and 350 °C, which presents a non-negligible potential for a cogeneration system. This study compares the thermal performance of different cogeneration plant configurations (KCA, KCB, and KCC systems) using the Kalina cycle to determine the best one. Several assumptions were made to reduce the complexity of the model. MATLAB and Excel software were used to solve the system of equations. After extensive analysis of the results, the KCA system showed the best performance, compared to the KCB and KCC systems, with a thermal efficiency of 22.15%, an exergy efficiency of 45.12%, and a net electrical capacity of 2565.03 kWe. Model sensitivity to concentration, temperature, and pressure variations also gave the KCA system the best-performing system. Evaluation of the excess heat flux removed from the process yields values of 7368.20 kW, 7421.86 kW, and 8094.15 kW for the KCA, KCB, and KCC systems. The results of this article serve as a decision support tool for installing the cogeneration system via the Kalina cycle in cement installations.