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METHANE HYDRATES

Methane hydrates, a promising natural gas resource, are believed to reside throughout the globe in sea-floor sediments and permafrost Methane hydrate isn't a familiar term to most, but it is gaining popularity in the energy sector. In the realm of energy R&D, methane hydrates are being evaluated as a potential fuel for the future. Some believe there is enough methane in the form of hydrates-methane locked in ice-to supply energy for hundreds, maybe thousands, of years. The Gas hydrates are clathrate compounds. A clathrate is a structure in which water molecules under certain conditions bond to form an ice-like cage that encapsulates a gas molecule, known as a guest molecule. When that guest is a methane molecule, it is methane hydrate. Methane hydrates, which form at low temperature and high pressure, are found in sea-floor sediments and the arctic permafrost. They can be scattered through several-hundred-meter depths and at various concentrations.

Although some research has been carried out in the past, little is known about the location, formation, decomposition, or actual quantities of methane hydrates. However, methane hydrates should be evaluated as a potential primary energy source for the future. Furthermore the natural gas /CNG infrastructure is growing also. Much of industry has already converted to natural gas. Public utilities are headed that way as well.

The following elements will have to be examined:

• Resource characterization: Essentially research toward understanding how methane hydrates behave, where and how they occur and what energy potential they actually represent.
• Production: Methods of harvesting/mining methane hydrates will have to be developed. Production methods for methane hydrates will probably be similar to those of the oil and gas industry.
• The carbon cycle: Since methane is a greenhouse gas, understanding methane as a primary gas or a trace gas will be important in today's climate change initiatives. Although methane when burned is a clean fuel, more information is needed on the emissions from various methane sources to fully understand its atmospheric implications.
• Sea-floor Stability/Safety: The oil and gas industry continues to explore deeper beneath the ocean floor. Industry has concerns about drilling through hydrate zones, which can destabilize supporting foundations for platforms and production wells. The disruption to the ocean floor also could result in surface slumping or faulting, which could endanger work crews and the environment.
• Hazards arise because gas hydrates are only quasi-stable; if the temperature is increased at a fixed pressure or the pressure decreased at fixed temperature, or both temperature increased and pressure decreased, it is easy to pass out of the stability regime of hydrates. The hydrate structure encases methane at very high concentrations. A single unit of hydrate, when heated and depressurized, can release 160 times its volume in gas.

Estimates

Estimates on how much energy is stored in methane hydrates range from 350 years' supply to 3500 years' supply based on current energy consumption. That reflects both the potential as a resource and how little is really know about the resource.

TECHNOLOGY:
FUTURE TECH:

Here are some technologies, which have a great potential in the automobile industry. Technologies those are particularly suitable for of mass customization and the more extreme build-to-order (BTO) approach. A brief look into Hydroforming, Dieless NC forming and Friction stir welding.

HYDROFORMING PROCESS

Hydroforming is a metal forming process that relies on fluid pressure to shape the metal piece

Hydroforming consists of two divisions, tube and sheet metal forming. The two divisions are processed using similar techniques that are developed to accommodate the different products. The basic principals for the different techniques are to utilize fluid pressure to form a part. Hydroforming differs from conventional deep drawing processes in that it replaces the die tool with a rubber diaphragm that is backed with fluid pressure to form the part to the punch tool. Relating this concept to a tubular part, the tube is placed in a die then the tube is filled with a fluid pressure to form the part to the die. Standard hydroforming techniques start with a CNC bent tube or sheet of metal. The part is then placed in the tool, followed by the cycling of the press to clamp the tool shut. "Low pressure" forming is ideal for parts with large radii, simple cross sections and parts with flat surfaces. If a "high pressure" is used the part will conform to complex cross sections with small radii. The drawback to high pressure forming is that due to friction the part will have non-uniform thickness. The latest buzzword in the hydroforming industry is a process called "active hydroforming". In active hydroforming the part is placed in the tool. However, before the tool is cycled shut a fluid pressure is applied to expand the part while holding a uniform thickness. From here the press is cycled and the part is formed. The resulting part will have uniform thickness and form to complex cross sections. Active hydroforming takes the strong points from high and low-pressure hydroforming and combines it to one process. Let's lead the market in this advanced hydroforming process. Chamber pressure and part lubrications are critical parameters in the hydroforming process and require some part testing to develop the right mix for the two. The forming press must be able to overcome the die separation force that is generated by the pressure in the tube

Advantages

The first, and probably most obvious, advantage is that only a single die and a blank holder is needed. There is no need to fit a female die to the punch, which means that more complex shapes can be easily formed. The single die setup also improves the speed at which die changes can be made. Since the pressure is adjusted on a continuous basis, parts, which might take two or three conventional deep draws, can now be done in one operation.

The flexible diaphragm helps eliminate the marks that are usually formed in deep drawing operations. This reduces costs that are related to the finishing of the final part. Due to the fact that the metal is not bent or stretched but formed around the punch, the material thin out in the walls of the part is usually less than 10%. Thus, thinner blanks can be used to form the parts desired. This is good when using expensive materials or when weight is of critical concern, as it is in the aerospace industry. At the same time, the material is not work-hardened as it would be for a normal drawing process, so the end part usually does not have to be annealed.

Since the punch does not have to be made of hardened steel, cast iron is usually used to make the punch and blank holder. This material is easily machinable and has a long lifespan.

Difficulties

Some of the difficulties surrounding this process are the pressures involved in forming the piece. Because the pressures involved are usually three to four times those normally associated with deep drawing, careful attention should be paid to the pressure vessel so that none of the fluid leaks. If too little pressure is applied, the part will wrinkle, resulting in poor quality. If too much pressure is applied, the blank will sheer and the part will have to be scraped.

DIELESS NC FORMING

The dieless NC forming process was developed as a flexible, alternative manufacturing method to effectively prototype stampings and produce panels in small lot. It is a numerically controlled incremental forming process that can form various materials into complex shapes

3D CAD/CAM data is downloaded to the machine controllers 3-Axis Servo system. A blank is securely fixed to the X-Y table. The table and vertical tool (Z-Axis) are actuated simultaneously. The XY table moves in a circular or oval direction to the tool path data. The spherically tipped Z-Axis tool incrementally descends compressing and stretching the sheet to the desired shape. . It is extremely cost effective as conventional tooling is not required and time to market is greatly reduced. Dieless NC forming is suitable for small lot production, rapid prototyping and production of service parts.

Advantages Tooling is greatly reduced. Prototyping is faster and inexpensive. Digital data forming provides for easy modification of part. Easy operation with three axes NC program. Quiet and safe operation requiring little floor space.

Applications

Small Lot Production-One of the main advantage of NC forming is that the tooling costs are 5~10% of conventional stampings. However, the forming process is quite slow. Thus this process is suitable for low volume production in the magnitude of 1~500 pieces per month. It is an extremely flexible system as many different parts can be run on the same machine.

Service Parts-A major challenge, in the automotive industry, is the necessity of storing tooling for long periods of time. With this new process, those tools could be discarded, and Dieless NC forming machines can be employed to produce service parts upon demand.

Rapid Prototyping- This system is ideally suited for rapid prototyping as development time and tryout costs are greatly reduced. No hard tooling is required and design CAD data can be transferred to the machine controller easily. Depending on the part size, a prototype panel could be produced nearly instantly upon receipt of the CAD data

Ref:DIELESS NC FORMING.

FRICTION STIR WELDING

Friction Stir Welding, a process invented and patented by TWI, is a highly significant advancement in aluminum welding technology that can produce stronger, lighter, and more efficient welds than any previous process and is currently being used to produce components in the Aerospace Industry, as well as in shipbuilding, rail car manufacturing, construction, and other related industries.

In the Friction Stir Welding process, a welding tool moves along the area to be joined while rotating at a high speed. This action between the tool and the aluminum creates frictional heat, which softens the aluminum but does not melt it. The plasticized material is then, in essence, consolidated to create one piece of metal where there were originally two. The weld is left in a fine-grained, hot worked condition with no entrapped oxides or gas porosity.

Higher Properties & No Heat Distortion

Friction Stir Welding does not create a heat-affected zone nor does it use welding consumables. Since traditional heating methods are not employed, the properties of the metal in the joined area are higher than those from any other known welding process and distortion is virtually eliminated.

Friction Stir Welding works with all aluminum alloys and can be used to join dissimilar alloys and wrought products to cast products. The process needs no post treatment.