Parametric Theoretical Study of Solar Assisted Cooling System Using Lithium Bromide-Water Pair

In this paper, the effect of parameters of solar absorption system such as evaporator, absorber, condenser, generator temperatures and the mass of the solution on the evaporator cooling load and the coefficient of performance has been explained theoretically. The results show that, increasing of evaporator and condenser temperatures increase the evaporator cooling load, performance coefficient and the Ratio of Circulation while increasing the temperature of condenser and absorber decreases the evaporator cooling load, performance coefficient and the Circulation Ratio. In addition, increasing the solution mass increases the refrigeration power while the performance coefficient and the Circulation Ratio was constant at increasing the solution mass. The reached maximum cooling load was (1.932 kW) at 15 kg solution mass and 100 °C generator temperature, the maximum COP was 0.774 at (10 °C) temperature of evaporator and the peak Circulation Ratio was 0.3066 at (30 °C) temperature of absorber and (100 °C) temperature of generator.

RESEARCH OF METHANE PRODUCTION PROCESS FROM BIOGAS AND PYROLYSIS GAS

The article investigates the separation process of biogas and the pyrolysis gas by application of membrane technology. The urgency of the problem of purification of industrial, agricultural, distillery waste or waste water by means of biological fermentation in anaerobic conditions of organic substances is indicated. If it is not possible to biodegrade waste, use pyrolysis or gasification. Pyrolysis gas, unlike biogas, has hydrogen and carbon monoxide. The process of separating methane from leaving impurities is much more economical than the process of removing impurities to obtain methane. Although for more than a hundred years mankind has known about the principles of gas diffusion and mass transfer through polymer films. But only in the last 40 years, membranes have begun to be used on an industrial scale in gas purification. With a membrane unit, a high methane production efficiency (> 96%) can be achieved. The lack of mechanical complexity and their modular design, which allows them to scale easily to provide significant flexibility, are increasingly gaining attention from the industry. The paper was proposed setting circuit for isolating methane and its operation is described. As a result of the research carried out, graphical dependencies were obtained at the stages: absorption (volume fraction of dissolved methane from the circulation ratio of the absorber), adsorption (absorption capacity of the membrane packing over time) and regeneration (the rate of desorption of the absorber from the membrane packing versus time). Using these dependencies, it is possible to calculate the flow rate of the absorber that is used in the absorption process and to determine the number of membrane elements for the membrane apparatus.

The Influence of Watershed Morphometry to River Discharge Variation (Case Study of Bengkulu Watershed, Indonesia)

Morphometric analysis in a watershed is a requirement in analyzing hydrological conditions in a watershed, because the properties of river networks and their relationship to each other will affect the condition of water resources in the watershed. This study aims to analyze the variations in the discharge of two rivers in the upper Bengkulu watershed and the morphometric aspects that influence it. For this reason, several morphometric aspects are calculated, such as the area of the watershed, circulation ratio, median elevation and slope. The results showed that the Rindu Hati River had a higher monthly discharge than the Susup River. The sizeable difference in discharge between the Rindu Hati and Susup Rivers is due more to differences in the size of the area. As is known, the total area of the Rindu Hati Sub-watershed is 184.2 km2, while the Susup Sub-watershed is 103.6 km2. With a large area, the Rindu Hati Subwatershed will be able to accommodate a large amount of rainwater as well.

Desired Circulation Ratio for Natural Circulation in Water-Tube Boiler

The basic objective of the paper is to identify the desired circulation ratio for the natural circulation of water tube boilers in different operating conditions. This requires the basic study of heat flux and the mode of the boiling heat transfer, and the phenomenon like a departure from nucleate boiling and tube overheating. The parameters, which need to be studied are heat flux, pressure, dryness fraction, void fraction, liquid velocity and their impact on the required circulation ratio. The present work is to develop a circulation analysis model for the natural circulation of the water tube boiler and to check the boiler design for different failure modes. For a natural circulation boiler, the circulation ratio is one of the most important design parameters as the other design parameter like critical heat flux and skin temperature are mainly derived from the circulation ratio. The required circulation ratio can vary with the boiler pressure, liquid velocity and maximum heat flux. This study is intended to provide input for the safe and optimum design of a natural circulation boiler.

The effects of exhaust gas re-circulation and injection timing on combustion performance and emissions of biodiesel and its blends with 2-methylfuran in a diesel engine

In this study, the influences of injection timing and exhaust gas re-circulation on combustion and emissions characteristics of biodiesel/2-methylfuran blends are investigated on a modified water-cooled 4-cylinder four-stroke direct injection compression ignition engine. The experimental conditions are, respectively, to adjust injection timing and exhaust gas re-circulation ratio at 0.38 MPa break mean effective pressure with the engine speed at 1800 rpm constantly. With injection timing in advance, the peak cylinder pressure rose while maximum heat re-lease rate first decreased and next slightly raised. Ignition delay and brake specific fuel consumption reduced first and then raised while combustion duration and break thermal efficiency had the opposite trend. The NOx emissions in-creased, and HC emissions first reduced significantly and then slightly increased, while 1,3-butadiene and acetaldehyde emissions presented a reduction tendency. As exhaust gas re-circulation ratio increased gradually, ignition delay as well as combustion duration was prolonged. brake specific fuel consumption increased and break thermal efficiency declined. HC, CO, 1,3-butadiene, and acetaldehyde emissions raised while NOx emissions reduced significantly. Biodiesel could be-have well in a Diesel engine and thus a feasible alternative fuel for diesel. More-over, methylfuran addition into biodiesel could raise break thermal efficiency and the break thermal efficiency of BM20 is higher than BM10. However, both BM10 and BM20 appeared a combustion deterioration when injection timing at 2.5?CA before top head center.

Alternative Refrigerants for Solar Absorption Air-Conditioning

Three hydrocarbons are considered as refrigerants for solar absorption air-conditioner. The cooling plant is composed essentially of the absorption chiller and the solar system is simulated with three working pairs: propane/octane, butane/octane and iso-butane/octane. Results are compared to those of ammonia/water mixture at the same fixed operating conditions and assumptions. The main advantages of the investigated refrigerants are their similar cooling effect compared to ammonia with a coefficient of performance reaching 0.63 and their relatively low working pressures. Nevertheless, the circulation ratio for hydrocarbon mixture is higher compared to ammonia. Propane/octane working mixture seems to be suitable for solar absorption air-conditioners with some particular precautions. The heat required to drive the absorption system is provided by evacuated tubes solar collectors of 90[Formula: see text]m2, a value in agreement with commercialized solar absorption air-conditioner operating with ammonia.

The Effect of Gas Circulation on the High-Pressure Synthesis of Long-Chain С35+ Hydrocarbons from CO and H2

The effect of gas recirculation on the production of long-chain C35+ hydrocarbons over supported Co-Al2O3/SiO2 catalyst at a pressure of 6.0 MPa, temperature 225 °C and gas hourly space velocity 1000 h–1 was studied. It was shown that the circulation mode provides isothermicity of the catalyst bed and increases the selectivity to C35+ hydrocarbons and their output. The study revealed that the catalyst deactivation rate decreases by a factor of 8 when the circulation ratio is raised from 2.2 to 6; therewith, the content of unsaturated hydrocarbons in the synthesis products increases twofold.