THE EFFECT OF PLATE GEOMETRY OF FLAT PLATE SOLAR COLLECTOR UNDER VARIABLE HEAT FLUX

In the current study, the effect of different plate geometry namely smooth plate (traditional model) and V-corrugated plate (new model) on the output of the FPSC is conducted numerically and experimentally. The outdoor experimental work has been done in Baghdad- Iraq. All geometric models and the numerical simulations were carried out in the current study using the commercial CFD method, ANSYS 19. R3. The results indicated that the difference between numerical results and experimental findings is 8.12 % for average water temperature in a tank, while the working fluid temperature at the exist of riser pipe is about 8.36 %. The thermal performance for the new model is found higher than that for traditional model. The thermal performance of new model in terms of water temperature inside the tank was found higher than traditional model by 10.7 %. In addition, the overall thermal efficiency of collector for the new model has been increased about 9.9 % than traditional model.

Experimental Evaluation of Airlift Performance for Vertical Pumping of Water in Underground Mines

This paper presents experimental studies on the optimization of air–water flow in an airlift pump. Airlift pumps use compressed gas to verticall transport liquids and slurries. Due to the lack of theoretical equations for designing and predicting flow regimes, experimental investigations must be carried out to find the best condition to operate an airlift pump at high efficiency. We used a new air injection system and different submergence ratios to evaluate the output of a simple pump for vertical displacement of water in an underground mine. The tests were carried out in a new device with 5.64 m height and 10.2 cm circular riser pipe. Three air-jacket pipes, at different gas flows in the range of 0.002–0.09 m3/s were investigated with eight submergence ratios. It was found that with the same air flow rate, the most efficient flow of water was achieved when an air jacket with 3 mm diameter holes was used with a submergence ratio between 0.6 and 0.75. In addition, a comparison of practical results with two theoretical models proposed by other investigators showed that neither was able to accurately predict airlift performance in air–water flow mode.

Experimental Study on Plugging Inside a Pipe Using Carbonated Ice as a Substitute for Methane Hydrate

Methane hydrate has been found below the seafloor in the Exclusive Economic Zone (EEZ) of Japan in a large amount. During the methane hydrate transportation, it is concerned that the riser pipe or the flowline can be plugged by the hydrate reformation and the freezing of seawater. The degradation and reformation kinetics of methane hydrate are mainly controlled by temperature, pressure, and methane concentration in the system; however, it is difficult to predict these factors in the multiphase flow because they are affected by fluid dynamics and heat transfer. To obtain the experimental data of the degradation kinetics, we developed a closed-loop experimental apparatus consisting of jacketed tubings used as heat exchangers, three acrylic units to observe the flow, and a slurry pump. The flow rate, salinity, temperature, and pressure in the apparatus were continuously measured in the circulation experiments. The experiment results showed that the freezing condition of the fluid in the pipe is affected by the temperature of the outside of the pipe or the particle in the fluid. This paper reports some experimental data obtained in several cases, including those conducted under freezing conditions.

Risk Assessment of the Large-Scale Hydrogen Storage in Salt Caverns

Salt caverns are accepted as an ideal solution for high-pressure hydrogen storage. As well as considering the numerous benefits of the realization of underground hydrogen storage (UHS), such as high energy densities, low leakage rates and big storage volumes, risk analysis of UHS is a required step for assessing the suitability of this technology. In this work, a preliminary quantitative risk assessment (QRA) was performed by starting from the worst-case scenario: rupture at the ground of the riser pipe from the salt cavern to the ground. The influence of hydrogen contamination by bacterial metabolism was studied, considering the composition of the gas contained in the salt caverns as time variable. A bow-tie analysis was used to highlight all the possible causes (basic events) as well as the outcomes (jet fire, unconfined vapor cloud explosion (UVCE), toxic chemical release), and then, consequence and risk analyses were performed. The results showed that a UVCE is the most frequent outcome, but its effect zone decreases with time due to the hydrogen contamination and the higher contents of methane and hydrogen sulfide.

Combined Mining and Pulp-Lifting of Ferromanganese Nodules and Rare-Earth Element-Rich Mud around Minamitorishima Island in the Western North Pacific: A Prefeasibility Study

An examination of the technical and economic feasibility of the combined mining of the rare-earth element-rich mud (REE-rich mud) and ferromanganese nodules (FN) around Minamitorishima (Marcus) Island in Northwest Pacific is introduced. A previous study showed that the mining of REE-rich mud around Minamitorishima Island was not economically feasible. Therefore, in this study, three changes from the previous mining model to improve its economy are proposed. The first one is combined mining with FN in the area. The second one is introducing a pulp-lifting system that can lift both REE-rich mud and FN at high concentrations through a riser pipe. The third one is the reuse of waste mud and processed slag for construction materials. The economic evaluation results show a change from a slightly negative to quite positive economy depending on the mixing ratio of REE-rich mud and FN in the pulp-lifting. In addition, some technical approaches necessary to realize the combined mining method are introduced.

Sour-Service Risers and Accessories for HP/HT Application in the Gulf of Mexico

This article, written by JPT Technology Editor Judy Feder, contains highlights of paper OTC 30558, “Development and Implementation of Heavy-Wall, High-Strength, Sour-Service Accessory and Risers for HP/HT Application in the Gulf of Mexico,” by Carine Landier, Jonathas Oliveira, and Christelle Gomes, Vallourec, et al., prepared for the 2020 Offshore Technology Conference, originally scheduled to be held in Houston, 4–7 May. The paper has not been peer reviewed. Copyright 2020 Offshore Technology Conference. Reproduced by permission. As oil and gas development in the Gulf of Mexico increasingly requires high-pressure/high-temperature (HP/HT) applications, the need for sour-service (SS) resistance also has grown. To meet these needs, continual innovation and improvement is needed in SS-grade materials from a technical and cost-effectiveness perspective. The complete paper discusses the material properties achieved with several large-diameter, heavy-wall SS pipes. The complete paper presents a detailed, illustrated discussion of the applications for the high-strength SS pipe and its manufacturing process. Applications The authors write that improved materials to meet HP/HT requirements such as those in the Gulf of Mexico are needed particularly for two applications: for risers, which require high-strength, thick-wall sour service; and as a substitute for corrosion-resistant alloy (CRA) with sour carbon material on defined accessories. Vallourec has developed high-strength [125,000-psi specified minimum yield strength (SMYS)] and resistant carbon steel pipes in sizes with outer diameter (OD) up to 23 in. and wall thickness up to 2.5 in. These sizes are common in lower-strength material, but meeting the high-pressure requirements with higher-grade material enables cost savings and eliminates some CRA components. It also enables the use of much-lighter-weight pipe than the 80,000-psi SMYS material that is standard for SS applications in oversize OD and heavy wall. Risers. Most deepwater drilling is performed with classic subsea blowout-preventer (BOP) systems. Access to the well through the BOP is accomplished with low-pressure, large-diameter (19-in. internal diameter) drilling riser pipe. Pipes are supplied in weldable grades (API 5L X65–X80). Large-diameter forged flanges are then welded onto the tubes. Connections are made by multiple bolts. High pressures, required as part of the drilling process, are supplied by small-diameter choke-and-kill lines. This system has served the industry well, but, as well pressures increase, so have cost and feasibility requirements of subsea BOP technology. These costs, driven by the complexity of redundant systems, have driven a desire to explore an alternative solution—a surface BOP with high-pressure drilling riser pipe. Using a surface BOP reduces the complexity and cost of the system significantly because of the ability to inspect it. The drilling riser then carries the pressure to the surface and must be able to contain it. The high-pressure environment that instigated a new solution was based on a 15,000-psi well pressure with NACE Region 2 SS performance. Because of the requirement for weldable grades for attaching the flange as well as SS, the maximum yield strength has been limited to 80,000 psi. At that strength, a very high wall thickness is required to meet 15,000 psi and greater. This becomes very heavy and can be limited by the rig hook-load capacity. Alternatives in weldable grades are nickel-based alloys with SS performance. A full string, however, is prohibitively expensive.