Liquid Metal Batteries

 

Battery storage capacity is an increasingly critical factor for reliable and efficient energy transmission and storage—from small personal devices to systems as large as power grids.                                                                                                                              

    This is especially true for aging power grids that are overworked and have problems meeting peak energy demands. Companies are scrambling to develop scalable battery solutions that can stabilize these grids by increasing energy efficiency and storage capacity.

    The liquid metal battery is based on research conducted at the Massachusetts Institute of Technology.Tests with cells made of low-cost, Earth-abundant materials confirm that the liquid battery operates efficiently without losing significant capacity or mechanically degrading — common problems in today’s batteries with solid electrodes.

How does it work?

     In most batteries, the electrodes — and sometimes the electrolyte — are solid. But in a liquid metal battery, all three are liquid.Two liquid electrodes (magnesium and antimony) are separated by a molten salt electrolyte; The negative electrode — the top layer in the battery — is a low-density liquid metal that readily donates electrons. The positive electrode — the bottom layer — is a high-density liquid metal that’s happy to accept those electrons. And the electrolyte — the middle layer — is a molten salt that transfers charged particles but won’t mix with the materials above or below. Because of the differences in density and the immiscibility of the three materials, they naturally settle into three distinct layers and remain separate as the battery operates.

 

When a liquid metal battery cell is at operating temperature, potential energy exists between the two electrodes, creating a cell voltage. When discharging the battery, the cell voltage drives electrons from the magnesium electrode and delivers power to the external load, after which the electrons return back into the antimony electrode. Internally, this causes magnesium ions to pass through the salt and attach to the antimony ions, forming a magnesium-antimony alloy. When recharging, power from an external source pushes electrons in the opposite direction, pulling magnesium from the alloy and redepositing it back onto the top layer.

How is it better than other batteries?       

    The liquid metal battery platform offers an unusual combination of features. In general, batteries are characterized by how much energy and how much power they can provide. (Energy is the total amount of work that can be done; power is how quickly work gets done.) In general, technologies do better on one measure than the other. For example, with capacitors, fast delivery is cheap, but abundant storage is expensive. With pumped hydropower, the opposite is true.

     But for grid-scale storage, both capa­bilities are important — and the liquid metal battery can potentially do both. It can store a lot of energy (say, enough to last through a blackout) and deliver that energy quickly (for example, to meet demand instantly when a cloud passes in front of the sun). Unlike the lithium-ion battery, it should have a long lifetime; and unlike the lead-acid battery, it will not be degraded when being completely discharged. And while it now appears more expensive than pumped hydropower, the battery has no limitation on where it can be used. With pumped hydro, water is pumped uphill to a reservoir and then released through a turbine to generate power when it’s needed. Installations, therefore, require both a hillside and a source of water. The liquid metal battery can be installed essentially anywhere. No need for a hill or water.

    Liquid electrodes offer a robust alternative to solid electrodes, avoiding common failure mechanisms of conventional batteries, such as electrode particle cracking.

 

Other advantages of liquid metal batteries include:

  • Modular design that can be customized to meet specific customer needs
  • Because the components are liquid, the transfer of electrical charges and chemical constituents within each component and from one to another is ultrafast, permitting the rapid flow of large currents into and out of the battery.
  • Negligible cycle-to-cycle capacity fades over thousands of cycles and years of operation because the electrodes are reconstituted with each charge.
  • Uses inexpensive, earth-abundant materials
  • Can respond to grid signals in milliseconds
  • Stores up to 12 hours of energy and discharges it slowly over time
  • Operates silently with no moving parts, easy to install

 

What is its role in the future?   

  The novel rechargeable battery could one day play a critical role in the massive expansion of solar generation needed to mitigate climate change by mid-century.

The ability to store large amounts of electricity and deliver it later when it’s needed will be critical if intermittent renewable energy sources such as solar and wind are to be deployed at scales that help curtail climate change in the coming decades. Such large-scale storage would also make today’s power grid more resilient and efficient, allowing operators to deliver quick supplies during outages and to meet temporary demand peaks without maintaining extra generating capacity that’s expensive and rarely used.

 

However, there are some disadvantages to the liquid metal battery:

  • High operating temperatures
  • Extremely heavy, this makes its energy density(<200 Wh/kg) considerably less than lithium-ion batteries
  • Since they are in liquid form, that they are not well suited to mobile applications
  • There is a very high possibility of potential leak

Bringing it to market

    Ambri (formerly Liquid Metal Battery Corporation) is developing an electricity storage solution that will change the way electric grids are operated worldwide.

Ambri has now designed and built a manufacturing plant for the liquid metal battery in Marlborough, Massachusetts. As expected, manufacturing is straightforward: Just add the electrode metals plus the electrolyte salt to a steel container and heat the can to the specified operating temperature. The materials melt into neat liquid layers to form the electrodes and electrolyte. The cell manufacturing process has been developed and implemented and will undergo continuous improvement. The next step will involve automating the processes to aggregate many cells into a large-format battery including the power electronics.

    Ambri has not been public about which liquid metal battery chemistry it is commercializing, but it does say that it has been working on the same chemistry for the past four years.

    Ambri researchers are now tackling one final engineering challenge: developing a low-cost, practical seal that will stop air from leaking into each individual cell, thus enabling years of high-temperature operation. Once the needed seals are developed and tested, battery production will begin.

Graphene and Carbon nanotube

For years, researchers have known that carbon, when arranged in a certain way, can be very strong. Case in point: graphene.

Graphene-a one  atom  thin  sheet  of  carbon  atoms  arranged  in a  hexagonal  format  or  a  flat  monolayer  of  carbon  atoms  that  are  tightly  packed  into  a 2D  honeycomb  lattice  is  the  ‘new  wonder   material’ that  is  expected  to  shape  almost  all aspects  of  future  technologies.  Existing  as  the  sole  2D  structure  on  earth  a lot  is  expected  of  this  material.

Graphene has many fascinating properties. It is about 200 times stronger than the strongest steel. It efficiently conducts heat and electricity and is nearly transparent. Graphene shows a large and nonlinear diamagnetism, greater than graphite and can be levitated by neodymium magnets.

To give you an idea of what graphene is capable of :

  • It can be stretched quarter its length and and it is stiffer than diamond thanks to its perfect crystalline structure and ultra strong interatomic bonds
  • It is so strong that it would take an elephant balancing on a sharpened pencil to pierce a graphene sheet with the thickness of a saran wrap
  • Because it is only one atom thick, a gram of graphene can cover an entire football stadium
  • At room temperature it conduct electricity faster than any other known material and 250 times more than silicon
  • It demonstrates high bio compatibility and can be used in bio medical applications
  • It conducts heat ten times better than copper
  • It absorbs 2.3% of white light

There is virtually no field in the future world where graphene is not a part of.The future scope of graphene may include:

  • Graphene polymer batteries can allow electric vehicles to travel at the range of 800 kmph
  • Ultrafast photonic computer chips that can run on light rather than electricity
  • Organic Light Emitting Diodes(OLEDs)
  • Flexible touch screen displays
  • Ultra thin thermal and pressure sensors
  • Super sensitive elastomer skin for robots.

Major advantages of graphene are :

  • It  is  the  thinnest  material  known  and  with  that  also  the strongest.
  • It  consists   of  a  single  layer  of  carbon  atoms  and  is  both  pliable  and transparent.
  • It is a superb conductor of both heat and electricity.
  • It  is  used  in  the  production  of  high  speed  electronic  devices  responsible  for  fast  technological  changes.
  • Chemical sensors effective at detecting explosives.
  • Membranes for more efficient separation of gases. These  membranes  are  made  from  sheets  from  which  Nano scale  pores  have  been created.
  • Transistors  that  operate  at  higher  frequency  as  compared  to  others.
  • It  has  led  to  the  production  of  lower  costs  of  display  screens  in  mobile  devices  by  replacing  indium-based  electrodes  in  organic  light  emitting  diodes(OLED)  which  also  lower  power  consumption.
  • Used in the production of lithium-ion batteries that recharge faster. These batteries use graphene on the anode surface.
  • Storing Hydrogen for fuel cell powered cars.
  • Low  cost  water  desalination  by  using  graphene-with  holes  the  size  of  a  nanometer  to  remove  ions  from  water.
  • Used  in the  production  of  the  graphene  condom  which  is  able  to  increase  sensation  and   is  much  thinner  than  latex  condoms.

Roadblocks:

  • One of the most expensive materials on the planet
  • Non renewable resource and incredibly hard to synthesize
  • While notable for its thinness and unique electrical properties, it’s very difficult to create useful, three-dimensional materials out of graphene
  • Being  a  great  conductor  of  electricity, although it  doesn’t  have  a  band  gap (can’t  be  switched  off). Scientists are working on rectifying this.
  • The  main  disadvantage  of  graphene  as  a  catalyst  is  its  susceptibility  to  oxidative  environments.
  • Research has proven that graphene exhibits some toxic qualities. Scientists  discovered  that  graphene  features  jagged  edges  that  can  easily  pierce  cell  membranes,  allowing  it  to  enter  into  the  cell  and  disrupt  normal  functions.

These  are  just  but  a  few  of  the  ‘wonder  material’s’  advantages  and  disadvantages  and  since  the  material  is  still in  the  research  stage  much  more  is  yet  to  be  revealed .

 

The da Vinci Robot

The human body is a rather untidy place where your organs, bones, flesh, muscles, arteries and connective tissue all compete for space and about 30 percent of world’s 232 million tissue surgeries result in complications. This is because surgeons vary greatly in training, dexterity, experience and decision making. Sometimes there are fine tremors of hands and uneconomical movements.

Complex surgical procedures like circular anastomosis involve stitching together two severed ends of the intestine. Stitch them too far apart or too loose and they will bleed. Tie them too tight, they will strangle and kill the tissue. By embedding the knowledge of the best surgeons in digital systems, these autonomous and semi-autonomous robots could deliver universal access to the best surgical techniques and could potentially be a solution to the problems in conventional surgical procedures.

Robots in the surgical suite are nothing new. The best known of them, the da Vinci robot, is more than 15 years old and has performed over 2 million operations worldwide.

The future of minimally invasive or laparoscopic surgery methods is full of promise as it reduces pain, cost, healing times, scarification, disability and morbidity. Robot-assisted surgery(RAS) enables surgeons to perform minimally invasive yet complicated procedures that are more precise and more controlled than conventional, ‘manual’ surgeries, even if performed by the most skilled surgeon with the steadiest of hands.

The da Vinci robot:

The da Vinci robot is a state of the art technology which enables remote surgery and teleoperation

There are two components of this system: The robot itself (which operates on the patient) and the separate control console (which is controlled by a surgeon).

The robot has three small, nimble robotic arms that attach to various instruments such as a scalpel, scissors or electrocautery instruments. each instrument can easily be swapped out for different functions. The last arm holds an endoscopic camera that gives the surgeon 3-D vision from the control console.

These robots have enabled surgeons the mobility and nimbleness to perform abdominal surgery within the limited space of the human body. Combine this nimbleness with 3D imaging technology and augmented reality and surgeons will be able to ‘see right through you’ by superimposing 3D information from CAT scans and MRIs onto the view of the actual tissue. This 3D virtual environment will enable the surgeon to ‘see the invisible’ as certain areas in the body can be ‘illuminated’ in order to track the movement of, for instance, cancer as it spreads through the lymphatic system, enabling the surgeon to intervene where possible. Apart from their primary focus, the abdomen, the bots are now also correcting vision problems, reshaping joints and even drilling into brains.

Drawbacks:

One of the biggest drawbacks of the da Vinci robot is that they work exclusively with solid objects like bones or eyes which remain stationary during surgery.

In contrast, soft tissues vary in shape and size from patient to patient, and they are, by definition, pliant. This is especially problematic when we want to stitch soft tissues together. Stitch them all together and each stitch will alter their shape. Sometime a stitch may even cover the previous stitch or hide the location of the next switch. Sometimes leaking blood obscures the tissue. Moreover, there is no fixed value of spacing and tension while.

The other drawbacks of the da Vinci robot include:

  • Very expensive and costly
  • Longer operating and anesthesia time
  • Since the robot has multiple arms, it takes skill and practice to work with the da Vinci robot
  • As with any surgical device, there is also the risk that the da Vinci robotic surgical system could malfunction or fail, leading to serious injury or the need to switch to another type of surgical approach.
  • No automation at all. The da Vinci is a teleoperated system, where the surgeon makes every decision and controls every move.
  • Very expensive and costly
  • Longer operating and anesthesia time
  • Since the robot has multiple arms, it takes skill and practice to work with the da Vinci robot
  • As with any surgical device, there is also the risk that the da Vinci robotic surgical system could malfunction or fail, leading to serious injury or the need to switch to another type of surgical approach.
  • No automation at all. The da Vinci is a teleoperated system, where the surgeon makes every decision and controls every move.

Turning Mechanism in Trains

Have you ever wondered what keeps the train on the track? How does a train follow the track during a circular path? After all, there is no steering nor a differential in a train. As a matter of fact, the wheels on either side are connected through an axle which makes them rotate with the same angular velocity

Many of us would think that the flanges on the wheels would do the job. But that is not the answer.

The flanges are just a safety device. If the flanges rub against the track, it gives a horrible noise and it is a huge waste of energy. Moreover, there will be wear of tracks and wheels.

The flanges are a secondary mechanism just in case the real mechanism fails  

There is something fundamentally different in the design of wheels of a train and an automobile.

So, why is it different on a train?

  • Unlike a normal locomotive, trains have a huge body
  • Trains don’t make sharp turns like an automobile

Hence adding a differential would be a potential waste of resources.

So, how does it go around a corner? The solution is simple and elegant and it lies in the geometry of the wheels and tracks

The wheels are tapered, conical in shape. That means they have a varying diameter at different points of contact.

Suppose the track curves left(as shown in the figure below), the whole wheel-set shifts a bit to the right.

This makes the point of contact of the right wheel is at a larger diameter of the cone. While the diameter at the point of contact on the left wheel is much smaller.
As both the wheels are connected by a solid shaft both the wheels must the same angular velocity, making them rotate at different speeds. This system essential replaces the need for the differential in trains.

This also solves another major problem: Whenever there is a bump on tracks, the wheels suddenly slide even when travelling on a straight track & there is a great danger of being derailed, so the same design helps to stabilize the train & to run smoother

The whole beauty of this system is that the amount of shift of the wheelset happens automatically, makes the train move on turns smoothly and keeps the train on track.

Hence the conical geometry along with the flanges ensures the train stays on the track

Video Credit: TheRussianRailways

Power Steering

power steering

Power steering

In heavy duty (dump) trucks and power tractors the effort applied by the driver is inadequate to turn the wheels. In this case a booster arrangement is incorporated in the steering system. The booster is set into operation when the steering wheel is turned. The booster then takes over and does most of the work for steering. This system called power steering uses compressed air, electrical mechanisms, and hydraulic pressure. Hydraulic pressure is used on a vast majority of power steering mechanism today.

2

When the steering wheel is turned, the worm turns the sector of the worm wheel and the arm. The arm turns the road wheel by means of the drag link. If the resistance offered to turn the wheels is too high and the effort applied by the driver to the steering wheel is too weak, then the worm, like a screw in a nut will be displaced axially together with the distributor slide valve. The axial movement of the distributor slide valve in the cylinder will admit oil into the booster cylinder through the pipe line. The piston in the booster cylinder will turn the road wheels via the gear rack, the toothed worm sector, arm and drag link. At the same time, the worm sector will act upon the work and will shift it together with the distribution slide valve to its initial position and stop the piston travel in the boost cylinder. When the steering wheel is turned in the other direction, the wheels will be turned appropriately in the same sequence.

3

The more the steering mechanism and wheels resist turning, the more the control valve is displaced. Hence, power assistance is always supplied in proportion to the effort needed to turn the wheels.

Electronic power steering

Electrically assisted power steering is used in some cars. The assistance can be applied directly by an electric stepper motor integrated with the steering column, or the steering mechanism, or it can be applied indirectly with hydraulic assistance pressurized by electric pump. EPS attached to the rack and pinion-steering-exists in Honda-City vehicles.

power steering

Electronic power steering Improves steering feel and power saving effectiveness and increases steering performance. It does so with control mechanisms that reduce steering effort. Nissan’s Blue Bird passenger car series use an electronically controlled three way power steering. This power steering is responsive to vehicle speed, providing maximum assistance as the speed rises. The driver can also select his or her own performance from three levels of assistance that make the steering effort heavy, normal or light.

 

BELT CONVEYOR TAKE UP DESIGN

BELT CONVEYOR TAKE UP DESIGN | CONVEYOR BELT TAKE UP SYSTEM | HORIZONTAL TAKE UP IN BELT CONVEYOR4    

Belt Conveyors for bulk materials:

Take up Arrangement:

All belt conveyors require the use of some form of take up device for the following reasons:

  1. To ensure adequate tension of the belt leaving the drive pulley so us to avoid any slippage of the belt.
  2. To ensure proper belt tension at the loading and other points along the conveyor.
  3. To compensate for changes in belt length due to elongation.
  4. To provide extra length of belt when necessary for splicing purpose.

Usually there are two types of take up arrangements.

These are:

  1. Fixed take up device that may be adjusted periodically by manual operation
  2. Automatic take up device (constant load type)
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Manual Screw Take Up:

The most commonly used manual take up is the screw take up. In a screw take up system the take up pulley rotates in two bearing blocks which may slide on stationery guide ways with the help of two screws. The tension is created by the two screws which are tightened and periodically adjusted with a spanner. It is preferable to use screws with trapezoidal thread to decrease the effort required to tighten the belt.

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The main problem with the use of manual take up is that it requires a vigilant and careful operator to observe when take up adjustment is required. Perfect tension adjustment with this system is also not possible. For these reason these devices are used only in case of short conveyors of up 60m length and light duty.

 

Automatic Take Up:

In automatic take up arrangement the take up pulley is mounted on slides or on a trolley which is pulled backwards by means of a steel rope and deflecting pulleys. The carriage travels on guide ways mounted parallel to the longitudinal axis of the conveyor, i.e., horizontally in horizontal conveyors (Ex.: Gravity type automatic take up arrangement) and at an incline in inclined conveyors. Hydraulic, Pneumatic and electrical take up devices are also used.

Automatic take up has the following features:

  1. It is self adjusting and automatic
  2. Greater take up movement is possible
    5

For the perfect conveying of materials, adding a resistance with the peripheral forces on the driving pulley of a belt conveyor is important. Some of the resistances are:

  1. The inertial and frictional resistance due to acceleration of the material at the loading area
  2. Resistance due to friction on the side walls of the skirt board at the loading area.
  3. Pulley bearing resistance applicable for other than the driving pulley
  4. Resistance due to the wrapping of the belt on pulleys
  5. Special resistances include
  6. Resistance due to idler tilting
  7. Resistance due to friction between material and skirt plate
  8. Frictional resistance due to belt cleaners
  9. Resistance due to friction at the discharge plough

Special resistances are usually small. Here the resistance due to idler tilting and skirt resistance is ignored. There being no discharge plough the resistance due to plough is ignored. For belt speeds greater than 3 m/s, the edge clearances are applicable.

 

Automatic transmission

typical-automatic-transmssion

In this fast moving and leisurely world it is important that we look at the automation of gear systems in car. With the development of technology it is now possible to shift gears in car automatically making human life more comfortable than before.
An automatic transmission also called auto, self-shifting transmission, n-speed automatic or AT, is a type of motor vehicle transmission that can automatically change gear ratios as the vehicle moves, freeing the driver from having to shift gears manually.

Like other transmission systems on vehicles, it allows an internal combustion engine, best suited to run at a relatively high rotational speed, to provide a range of speed and torque outputs necessary for vehicular travel. The number of forward gear ratios is often expressed for manual transmissions as well
the most popular form found in automobiles is the hydraulic automatic transmission. Similar but larger devices are also used for heavy-duty commercial and industrial vehicles and equipment. This system uses a fluid coupling in place of a friction clutch and accomplishes gear changes by hydraulically locking and unlocking a system of planetary gears. These systems have a defined set of gear ranges, often with a parking pawl that locks the output shaft of the transmission to keep the vehicle from rolling either forward or backward. Some machines with limited speed ranges or fixed engine speeds, such as some forklifts and lawn mowers, only use a torque converter to provide a variable gearing of the engine to the wheels.

 

 

Brain Wars | Episode 3 – Open lockers

Questions

A very rich celebrity decides to safeguard his wealth in a very
innovative way. He buys a cupboard having 10×10 indentical lockers
(numbered from 1-100) having single key. He passes through all the
lockers in numbered order and opens all of them. Then he goes to the
first locker and locks every alternate lockers till he reaches the
100th locker. Then he again goes to the first locker and opens every
third locker such that if the locker is already opened he closes it.
Simillary for the fourth pass he opens/locks every fourth locker and
continues the process for 100 passes. At the end of the 100th pass he
is left with few open lockers and uses them to keep his wealth. In
rest of the lockers he installs laser alarms so that even a wrong
selection of locker by the thief would lead him behind the bars. So
fellas do you have enough force to identify those wealthy lockers?

Answer:
Continue reading Brain Wars | Episode 3 – Open lockers

Brain Wars | Episode 2 – Light years?

Question:

Let’s say ISRO discovered life on a planet which is 40 light years away from Earth. So it sent a spacecraft to verify the discovery. The spacecraft can travel with a maximum speed of 70 lightyears/year ( using a Wormhole!) and any change in speed is instantaneous (i.e. time lost in acceleration and deceleration is negligible). At the midway crew members realized that they were traveling at the speed of 20 lightyears/year and decided to speed up the spacecraft. How fast do they need to travel the rest of the course to have an average speed of 40 lightyears/year? Given the speed limits of the spacecraft is it even possible?!

Answer:

Its impossible to have an average speed of 40 lightyears/year.

Continue reading Brain Wars | Episode 2 – Light years?