Ammonia Mass Flow Research Articles

Effects of using ammonia as a primary fuel on engine performance and emissions in an ammonia/biodiesel dual‐fuel CI engine

Ammonia is a promising alternative fuel that can replace current fossil fuels. Hydrogen carrier, zero carbon base emissions, liquid unlike hydrogen, and can be produced using renewable resources, making ammonia a future green fuel for the internal combustion engine. This study aims to show the procedure of utilizing ammonia as a primary fuel with biodiesel in a dual-fuel mode. Hence, a single-cylinder diesel engine was retrofitted to inject ammonia into the intake manifold, and then a pilot dose of biodiesel is sprayed into the cylinder to initiate combustion of the premixed ammonia-air mixture. The effects of various ammonia mass flow rates with a constant biodiesel dose on engine performance and emissions were investigated. Furthermore, a one-dimensional model has been developed to analyze the combustion of ammonia and biodiesel. The results reveal that 69.4% of the biodiesel input energy can be replaced by ammonia but increasing the ammonia mass flow rate slightly decreases the brake thermal efficiency. Moreover, increasing the ammonia load contribution significantly reduced the emissions of CO2, CO, and HC but increased the emission of NO. It was found that ammonia delayed the start of combustion by 2.6CAD compared with pure biodiesel due to the low in-cylinder temperature and the high resistance of ammonia to autoignition. However, the combustion duration of biodiesel/ammonia decreased 19CAD compared with only biodiesel operation at full load, since most of the heat was released during the premixed combustion phase. Highlights Ammonia biodiesel dual-fuel CI engine has been investigated experimentally. Maximum 69.4% of the input energy is provided by ammonia in reasonable operation. Higher ammonia contribution in the engine load delays the SOC and decreases the combustion duration. Significant reduction in CO2, CO, and HC emissions in the ammonia-/biodiesel-fueled engine.

A novel solar hydrogen production system integrating high temperature electrolysis with ammonia based thermochemical energy storage

In this paper, a novel solar hydrogen production system integrating high temperature electrolysis (using solid oxide electrolyzer cell) with ammonia based thermochemical energy storage is proposed for the first time. Without a significantly high concentration ratio, the thermochemical energy storage can upgrade relatively low-temperature solar energy to high-temperature reaction heat for high temperature electrolysis (HTE). Furthermore, thermal coupling of ammonia based thermochemical energy storage system, sCO2 Brayton cycle and HTE will result in substantially higher fuel production efficiency as compared to conventional low-temperature water electrolysis. A system model, including ammonia based thermochemical energy storage, sCO2 Brayton cycle and solid oxide electrolyzer cell (SOEC) system, has been developed using the Aspen Plus software implemented with user-defined Fortran subroutines. The models including reactors, sCO2 Brayton cycle and SOEC have been validated by comparing the model-generated results with the data from references. The effects of the endothermic reactor inlet temperature T2, charging loop ammonia mass flow rate ṁc, turbine inlet temperature T11 and current density J on the system performance have been investigated parametrically. The results show that the solar to hydrogen efficiency ηSTH increases with T2, T11 and J increasing. In addition, there is an optimum ηSTH by varying ṁc. Further, a maximum ηSTH = 26% has been obtained by optimizing the parameters in predefined ranges, which is 7% higher than the state-of-the-art of the solar HTE with TES. Based on a preliminary techno-economic analysis, the capital cost of the proposed system is estimated to be 9.28 $/kg H2, which is 18.9% lower than a typical photovoltaic based electrolyzer system. Therefore, the proposed system is economically feasible.

The Effect of Cordierite-Platinum SCR Catalyst on the NOx Removal Efficiency in an Engine Fueled with Diesel-Ethanol-Biodiesel Blends

Today, vehicles especially diesel engines emitted a large amount of NOx in the urban areas. So, it is required to find ways such as SCR catalysts to reduce this hazard pollutant emission. In this work, a 3D model of cordierite/Pt SCR catalyst has been developed by using AVL FIRE software to analyze the NOx conversion efficiency. The simulation was performed based on experimental tests conducted on a single-cylinder engine. The exhaust gas from the engine that appears at the inlet of the catalyst was measured for E20B50D30 (20% ethanol, 50% biodiesel, 30% diesel) D100, E10D90, E20D80, B25D75 and B50D50 fuel blends at the engine speeds of 1800, 2150 and 2500 rpm under full load. The results showed that an increase in the engine’s rotational speed resulted in a reduction of NOx conversion, and the conversion rate reaches its minimum value at speed of 2500 RPM for all fuel mixtures. Moreover, increasing the ammonia mass flow rate resulted in higher NOx conversion for all fuel mixtures. However, the effect of increasing ammonia flow rate from 0.2 to 0.3 kg/h on the NOx conversion is lower than that when the ammonia mass flow changes from 0.1 to 0.2 kg/h. The maximum NOx conversion rate was observed for the mixture containing 20% ethanol and 80% diesel at the rotational speed of 1800 RPM while the lowest conversion rate is observed for pure diesel fuel. According to the results, it was seen that the SCR catalytic process for fuel blends contained ethanol have a better performance to reduce the NOx pollutant compared to the mixtures containing biodiesel at lower engine speeds; but at higher rotational speeds ethanol and biodiesel has not a positive effect on the NOx conversion.

A non-intrusive method for evaluation ammonia mass flow rate in the condenser for diffusion-absorption refrigerators

Studies of diffusion-absorption (DAR) refrigerators have intensified, as well as the market's interest in increasing energy efficiency through cogeneration systems. Several studies have been published with the objective of improving the coefficient of performance, through the most different procedures. This article evaluates a non-intrusive method for the calculation of the ammonia mass flow rate at the inlet of the expansion device. The required parameters are geometric data and condenser temperature. The air-side convection heat transfer coefficient was calculated considering six empirical correlations. Then, throughout an energy balance in the condenser, the mass flow rate was computed. Four correlations predicted similar heat transfer coefficient. Thus, it is possible to estimate the ammonia mass flow using only the geometric data and the condenser temperatures. The strategy adopted to achieve this goal it was to use only the geometric data and the temperatures of the condenser and to calculate the energy balance in the superheated and saturation phases, since the absence of the subcooling in the condenser is a characteristic of the DAR cycle.

МАЛОИНЕРЦИОННЫЙ ТЕПЛООБМЕННИК АММИАК-АНТИФРИЗ ДЛЯ ИССЛЕДОВАНИЯ ПЕРЕХОДНЫХ ПРОЦЕССОВ В ЭЛЕМЕНТАХ ДВУХФАЗНОЙ СИСТЕМЫ ТЕРМОРЕГУЛИРОВАНИЯ СПУТНИКА

Technical progress entails the use of more powerful equipment on satellites. In connection with the growth of heat generation onboard the spacecraft, the task is to develop thermal control systems based on two-phase mechanically pumped fluid loop (2PMPFL). The advantage of such systems is the ability to transport a greater amount of heat, reduced to a unit of flow, than when using circuits with a single-phase coolant. The study of two-phase thermal control systems in terrestrial conditions is difficult because gravity affects the hydraulics and heat transfer of two-phase flows. Particularly difficult is the study of transients. This article presents the results of tests of a recuperative heat exchanger, which allows to study transient processes in 2PMPFL with high accuracy.It was designed and manufactured the heat exchanger of simple “tube in tube” type design. The thermal characteristics of the heat exchanger were determined on the experimental stand, which is a prototype of a closed-type 2PMPFL with ammonia coolant. Single-phase “liquid” modes, two-phase modes with low mass vapor content (up to 0.04), and single-phase transient modes were investigated. It has been experimentally determined that a heat exchanger under given conditions is capable of removing up to 1323 W of heat in a single-phase mode and up to 1641 W of heat - when operating in a two-phase mode. The data obtained in the course of the experiments allowed us to select the most appropriate known correlation for calculating the stationary characteristics of the heat exchanger with an error not exceeding 5%, which is a high indicator of accuracy for engineering calculations.The heat exchanger has low thermal inertia. The conclusion is relevant for the range of parameters: the ammonia temperature at the inlet is 24...60 ⁰C; antifreeze inlet temperature 5… 16 ⁰C; ammonia mass flow rate 8...17 g / s; mass flow rate of antifreeze 1...4 kg/min.Due to the low thermal inertia of the heat exchanger, it can be used to study transients with the rate of change of the coolant temperature at the inlet up to 1.85 K / min. You can use the stationary method of thermal calculation, i.e. calculate the transient process in the quasi-stationary approximation.

Experimental Investigation of Condensation Heat Transfer in Ammonia Evaporative Condensers

This paper reports experimental data obtained for ammonia condensation heat transfer in an evaporative condenser. Experiments were carried out on a specially designed set-up equipped with both measuring and control devices, and a data acquisition system. Experiments were conducted for ammonia saturation temperature of 22°C to 40°C and condenser heat rejection rate ranging from 2000W to 6000W, during steady state condensation of ammonia. The experimental investigation aimed to determine thermal performances of the ammonia evaporative condenser under different operating conditions, namely as a function of: temperature difference between ammonia condensation and inlet air wet bulb temperature, cooling water mass flow rate and ammonia mass flow rate. Water film temperature distribution along the condenser's height has also been studied. Experimental results have been further compared to data in the open literature by authors with similar experimental investigations. The paper concluded that experimental results are in fairly good agreement with other authors work and consequently reliable. The paper also addresses the current ecological aspect implied by refrigerants, by using ammonia. Apart from its attractive thermo-physical properties, as compared to HFCs, ammonia is also an environment friendly natural refrigerant, known for its zero ozone depleting potential and zero global warming effect.

Optimal fan speed and compression ratio of an air-condensed vapor-compression ammonia recycling system

In the technology of liquid ammonia modification, the ammonia is recycled by compression and condensation. To minimize the energy-consumption of ammonia recycling system, compression ratio and fan speed are optimized. Thermodynamic models for the compressor and evaporative condenser are developed respectively. Mathematical equations are given to determine the optimal compression ratio and the corresponding fan speed ratio. To solve the equations, a numerical algorithm is proposed. By controlling the fan speed, the matching of ammonia mass flow rate and air flow rate can be optimized, which brings about the minimal energy-consumption. When the wet-bulb temperature is 22 °C, the system energy-consumption could be saved by 10.8–12.9% under optimal compression ratio and fan speed.

Combination of genetic algorithm and computational fluid dynamics in combustion process emission minimization

A computational fluid dynamics (CFD) code was connected with a systematic optimization algorithm to find the optimum settings for nitric oxide (NO) emission minimization in the bubbling fluidized bed boiler. This approach is superior to the typical approach in which CFD is used to calculate only a few intuitively selected cases, and the best case found is treated as the ‘optimum’ solution. Ammonia injection (selective non-catalytic reduction) is applied to control NO emission in the modelled fluidized bed boiler. Design variables consisted of ammonia mass flow from distinct injections. Genetic algorithm (GA) was used for the optimization. The predicted NO emission was reduced approximately 15% with respect to the current operating point by the application of GA and CFD. The use of CFD connected with systematic optimization algorithm seems to be a promising design tool for combustion process optimization.

Second derivative spectroscopy for the determination of volatilized ammonia from urea-amended soil

A second derivative spectrometer custom fitted with a 1 m stainless steel White cell and maintained at 105°C is used to make real-time measurements of volatilized NH3 from urea-amended soil. Comparison of the technique to impinger data shows a 5-16% discrepancy between the two techniques; however, other experiments presented suggests that this is not real. Sulfur dioxide and nitrous oxide interferences are discussed, though they were not found to be present in this study. Instrument response time is shown to be fast if 67% of the total response is achieved in less than 5 min. Fast response is achieved for ammonia if wall-adsorption effects are minimal and if ammonia mass flow is maintained at 0.2 μg min(-1).