Thermal energy storage (TES) has become a key component in combined heat and power (CHP) generation, which enhances the load regulation capability. In line with that concept, the present work addresses a numerical study that aims at investigating and predicting the transient thermal behavior of a water thermocline storage tank that integrates into a CHP plant. Investigations are carried out on two distinct two-dimensional models. The first model studies thermocline characteristics of the heat storage system through a single charge/discharge operation. The influence of various operating parameters such as inlet flow rate and the inlet temperature of HTF are investigated. Results clarify that the thermocline thickness increases as the inlet flow rate increases and consequently, the heat storage/release period decreases. The second modified model discusses the technique of simultaneous charging and discharging operation applied in the CHP unit. Two types of operations are analyzing with (a) stable charging with continual discharging and (b) periodic charging with continuous discharging. The results ravel out that the mixing ratio of charging and discharging flow rate (Qc/Qd) has a strong influence on the operation performance. When the ratio of Qc/Qd > 1, the thermocline forms and its thickness increases with time increases. The thermocline thickness remains constant as this ratio declines to 0.625. In the case of periodic charging, both larger charging flow rate and shorter none-charging periods result in maintaining the discharge outlet temperature of HTF stable for heat supply net and discharge performance improved.

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This work presents an experimental study that aims at investigating the effect of loading-ratio of coal in a coal-diesel fuel mixture on the combustion characteristics and exhaust emissions. Sub-bituminous coal from El-Maghara coal mine is utilized. It is washed, dried, and grounded to particle sizing of ≤ 30 μm. The experiments are conducted inside a horizontal, segmented water-cooled cylindrical furnace fitted with a coaxial burner having a central air assisted atomizer for oil-coal mixture admittance. All experiments are executed at constant input heat of 350 kW and air to fuel ratio of 15:1 while varying the percentage (mass basis: 5% and 10%) of coal in the fuel mixture. The measurements within the flame zone include mean gas temperatures, dry volumetric analyses of species (CO2, NOx, and O2) concentrations, and the accumulative heat transfer to the cooling jacket along the combustor. All measurements are compared regarding the pure oil flame. The results indicate that increasing the coal- loading ratio up to 5wt% leads to a progressive increase in the accumulated heat transferred and the combustor overall efficiency from 40% to 58% within a percentage increase around 45%. In addition a slight reduction in mean gas temperature within the flame zone when compared with the pure oil flame. The reduced flame temperature due to increasing the coal-loading ratio, caused a decline in the volumetric concentrations of NOx from 100 ppm to 20 ppm as expected.

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