The idea is simple: it uses the evaporation of a liquid to absorb heat, making a cold environment. Refrigerator is designed to keep food cold because cold temperatures help food stay fresh longer. The activity of bacteria, which all food contains, will be slower in cold surroundings so that it takes longer for the bacteria to spoil the food.

What do actually happen inside a refrigerator? How can it be so cold like that? Well, it is simply one of the most important thermodynamic cycle: the refrigeration cycle. This is what happens to keep the refrigerator cool:

The refrigeration cycle

In the cycle, a circulating refrigerant such as Freon and ammonia enters the compressor as a vapor. The vapor is compressed at constant entropy and exits the compressor superheated. The superheated vapor travels through the condenser which first cools and removes the superheat and then condenses the vapor into a liquid by removing additional heat at constant pressure and temperature. Then, the liquid refrigerant goes through the expansion valve (also called a throttle valve) where its pressure abruptly decreases, causing flash evaporation and auto-refrigeration of, typically, less than half of the liquid.

That results in a mixture of liquid and vapor at a lower temperature and pressure. The cold liquid-vapor mixture then travels through the evaporator coil or tubes and is completely vaporized by cooling the warm air (from the space being refrigerated) being blown by a fan across the evaporator coil or tubes. The resulting refrigerant vapor returns to the compressor inlet to complete the cycle.

It is interesting to understand how the a box of refrigerator, which have a variety of shapes, sizes, and functions, actually operates based on a thermodynamic cycle. Do you imagine how difficult the food preservation is without this technology? Well, just don’t. And should any of you be interested in buying any kind of refrigerator, you can read these refrigerators reviews from Wize.com. In addition to your comprehensive understanding about the refrigeration cycle, you may sharpen you aesthetic skill a bit by reading their refrigerators reviews .

Majari Picks: Web-of-the-Month is Inkers.biz.

Ink? It is in your everyday life, almost in every aspect of our activity. In the morning we read our newspaper and get to school bringing all our books. In the afternoon we jot things down on our agenda and leave sticky notes to friends. At night we print a lot of school assignments from our computer. Ink is everywhere. What is ink?

An ink is a liquid containing various pigments (organic and inorganic) and/or dyes used for coloring a surface to produce an image, text, or design. Ink is used for drawing and/or writing with a pen, brush or quill. Thicker inks, in paste form, are used extensively in letterpress and lithographic printing. Generally, an ink consists of two components, the pigment and/or dye and the vehicle/solvent.

According to its purposes, ink is categorized into four types: writing ink, drawing ink, printing ink, and invisible ink. One of the most common ink type is printing ink, a mixture of dispersed pigment in a carrier media that forms liquid or gel which can be pressed and dried on a media. Printing inks are further broken down into two subclasses: ink for conventional printing, in which a mechanical plate comes in contact with or transfers an image to the paper or object being printed on; and ink for digital non-impact printing, which includes inkjet cartridges and electrophotographic technologies.

Printing Ink

Linseed oil, soybean oil, and heavy petroleum distillate, combined with organic pigments, are primary raw materials for solvent (called the vehicle) in color printing ink production. The pigments are made up of salts of multi-ring nitrogen-containing compounds (dyes), for example: yellow lake, peacock blue, phthalocyanine green, and diarylide orange. Inorganic pigments also are used in printing inks to a lesser extent. Some examples are chrome green (Cr₂O₃), Prussian blue (Fe₄[Fe(CN)₆]₃), cadmium yellow (CdS), and molybdate orange (a mix of lead chromate, molybdate, and sulfate).

Carbon black is the raw material for black ink. White pigments, such as titanium dioxide, are used either by themselves or to adjust characteristics of color inks. Inks also contain additives such as waxes, lubricants, surfactants, and drying agents to aid printing and to impart any desired special characteristics.

So what does the future hold for ink? Would ink someday become a history? Although there is a big tendency in people’s everyday life to use electronic devices instead of paper, the great paperless society hasn’t begun to show itself yet–people simply like paper too much. And as long as there’s paper, then there must be ink.

We proudly present this month’s Majari Special Edition: All About Coal. The series of articles published in June 2008 will mainly discuss about coal technology; including its theory of origin, current coal processing technology, and also the future development of coal utilization as clean and environmentally-friendly fuel. Futhermore, we will deliver you some Op-Ed articles about coal utilization in Indonesia as well; and we are really interested in your comments to the issues.

With several guest contributors who will elaborately share their knowledge, this month at Majari, you will have a comphrehensive understanding about coal combustion, fluidization, liqufaction, gasification, carbonization, and even the lab-work characterization. There is also some review about current coal breakthrough technology such as coal-bed methane (CBM), coal-water mixture fuel (CWM), coal-oil mixture fuel (COM), crude synthetic oil from coal (CSO), integrated coal gasification combined cycle (IGCC), and biogasification.

We really look forward to hearing your comments and suggestions.

See you in the next Majari Special Edition!

Salam Majari Kanayakan.

Majari Picks: Web-of-the-Month is Mailboxixchange.com

The mailbox concept is very simple; it collects all the letters and important stuffs in one compact dedicated container. In spite of the simple concept that mailbox may have, it has been a real life-saver in our life. Internet and e-mails may have taken some part of the role but still mailboxes have its own significant niche in our everyday communication.

There are a broad variety of shapes, sizes, and materials. Many stores sell the materials you will need to use for decorative mailboxes. Locking mailboxes made from durable, weatherproof materials are highly desirable due to the built in safety features and the long-lasting exterior. Various colors and shapes are available so you will be sure to match the color of your home perfectly or you may choose a mailbox that provides a striking contrast sure to be noticed by your friends and neighbors. Stainless steel, aluminum, and other materials will make your new locking mailbox an addition to your home that will endure through the worst weather for many years.

Stainless steel mailboxes
Stainless steel mailboxes is one of the most favorite material for mailboxes. Despite of its high durability, stainless steel can be easily formed into so many shapes; providing so many variety in the mail box design itself.

Aluminum mailboxes
Compared to stainless steel mailboxes, aluminum ones are usually cheaper. This is because the material cost of aluminum is also less expensive than stainless steel. Aluminum mailboxes have all of the advantages that stainless steel have and moreover aluminum ones have high resistance to bad weather and rains.

Wooden mailboxes
If you prefer a vintage touch in front of your house, wooden mailboxes is a good choice. Mail boxes that made of woods are now becoming a popular option for them who loves a unique and old-fashioned mailbox. Even so, wood is not a waterproof material so that good design and placement is futhermore needed.

If you want to have your creativity in practice, you can use any old materials that you may have lying around in your house. You can use cotton balls and color them with a marker or paint then glue them on your mailbox. Voila, you have your very-hand-made mailbox of you liking. If you want to have some insights in designing your own mailbox, you could check Mailboxixchange.com. They’re actually having a great affiliation deals - a $20.00 for you if you register.

And anyway, here is a brief interview with him.

Majari: “Hi, Sesep! Congratulations for being the January’s Author of The Month! Any surprise?”
Sesep: “Oh yeah?? Of course I am glad and I appreciate it very much..”

Majari: “Yes, you are. You article has made a lot of traffic until now. It’s one of most favorite article in Majari last month. Anyway, can you tell us once more, what was the final conclusion of your opinion about slow Pertamina growth compared to Malaysia’s Petronas?”
Sesep: “OK, I’ll try to answer this briefly. Basically there are technical and non-technical problems that influence the slow growth of Pertamina compared to Malaysia’s Petronas. I am not capable of answering the details about the negative sides of Pertamina but I think the government should cooperate well with Pertamina to help them solving their problems. We are as Indonesian people can also participate in many ways to help Pertamina.”

Majari: “So, what do you mean with the terms technical and non-technical problems? Are the uncooperative government regulations included in the non-technical problems?”
Sesep: “OK, maybe examples could make it clear. According to the source that I read, the profit sharing between Pertamina and the Indonesian government is 10:90; 10% for Pertamina and 90% for the government. The average yearly profit of Pertamina is about 27 billion rupiahs and only 2.7 billion goes to Pertamina. And, this is one simple example, do you know that they need at least 13 billion rupiahs to build a new refinery? And let’s do the math: they can only build a new refinery once in 5 years if they use all of the profits. That’s the technical problem, this is contrary to Malaysia’s Petronas because only 10% of their profit that goes to the Malaysian government. And about the non-technical problems; one of non-technical problem is BP MIGAS. BP MIGAS is starting to give trusts to foreign oil and gas companies to manage the fields in Indonesia. We can see ExxonMobil is managing the Cepu Block (oilfield) and BP is managing the Tangguh Field (gas field). And why are they doing that? Well, it will be a very long argument if we discuss about their reasons. Take a look at my article and you will know why.”

Majari: “That’s very interesting. But don’t you think that the problem is way too complex? And can you think of any other factors beside profit-sharing and BP MIGAS trust that has been influencing the slow growth of Pertamina?”
Sesep: “Do you mean the corruption activity like most of the people and media say?”

Majari: “Exactly, doesn’t it make everything worse if they conduct any corruption activities while the profit is already small in amount?”
Sesep: “Hahaha, you naked me straight to the point. It’s true I guess, everyone knows that corruption sucks. But again, it’s not my capability to explain that in details.”

Majari: “Yes, maybe just let us hand the problem to whom it may concern. Hehehe.. And, you’ve mentioned that we, as Indonesian citizens, can also help Pertamina to grow. So, can you tell us some examples that we can do?”
Sesep: “Nice question.. Ideally, we can be Pertamina’s employee and work there with the motivation to help Pertamina. But it doesn’t mean that we will not be able to help Pertamina if we aren’t their employee. One example is to try preferring Pertamina’s products to others or go to Pertamina’s Gas Stations to fill the gas for our cars and motorcycles. It is very simple but helpful.”

Majari: “Hmm.. that’s a good point. And what do you think about Pertamina in the future? Will they be better?”
Sesep: “I hope so.. If they can take care of their problems, they will be better. The government and BP MIGAS should also support Pertamina to solve all the problems there. I myself will be proud if Pertamina can improve their capability. Will you?”

Majari: “Definitely, we all should be proud of our own products and services, including Pertamina. And about the prize, what will you do about that?”
Sesep: “Are there any prizes?? Hahhaha, just kidding.. Hmm.. don’t even think about that yet. Watching movies, food hunting, etc. Just like everyone does to have fun, I guess. Hehehe. ”

Majari: “Yeah right! We guess there is zero probability that you forgot about the prize. Hahaha.. Anyway, Thank you for your time, Sesep! Hope to read another interesting articles from you! Any info about you next article?”
Sesep: “My next article?? Hmmm, it’s confidential.. Hahaha, just wait for my surprise.. Ok, thanks for majarikanayakan.com and also the commentators in my article. I really appreciate you all very much. Big sucess for majarikanayakan.com!”

Congratulations, Sesep! And is it today the Chinese’s new year? It must be really great to have angpou even if you are not celebrating the new year at all.

And, whose turn next? Submit your articles and let the comments flow!

Salam Majari Kanayakan.

And anyway, here is a brief interview with him.

Majari: “Hi, Wahyu! You are December’s Author of The Month! How do you feel about that?”
Wahyu: “Hi, Majari! Of course I feel so glad and surprise too!”

Majari: “Great! Anyway, can you tell us in a nutshell what the membrane technology are all about? Any advantages that it may have compared to prior technologies?”
Wahyu: “Sure, basically membrane is a separation technology. The components will be separated based on size and shape, using pressure and semipermeable membrane. Separation using membrane need less energy and less chemical additives.”

Majari: “Have the technology already been in Indonesia?”
Wahyu: “Yes, it has. It has been used for water purification process.”

Majari: “Can you tell us more about water purification? What exactly the membrane do in that process?”
Wahyu: “The membrane act as a filter to water impurities, such as suspended particles, organic material, even bacteria and virus, depend on type of membrane we use.”

Majari: “So you’re talking about making all the water purification process into one single membrane filtering??”
Wahyu: “Water purification consist a number of stages: sediment filter to trap particles including rust and calcium carbonate, activated carbon filter to trap organic chemical, then RO filter which trap carbon, metals (As, Hg, Pb, etc), even virus and bacteria; depend on size of the pores, and then second activated carbon filter to capture chemicals not removed by reverse osmosis filter, but it’s optional, and finally ultra violet lamp for disinfection any microbes that may escape the reverse osmosis filter.”

Majari: “Ohh.. so some of the traditional equipments may be substituted with membrane and the whole process will be better?”
Wahyu: “Yes, because by using membrane; in this case the RO membrane; we can remove particles up to 1 angstrom. It’s a small unit for particles, I think”

Majari: “Emm.. in the article you’ve mentioned about the hemodialysis process with membrane.. Can you elaborate more about that?”
Wahyu: “Hemodialysis is a process that is used to help people with kidney failures. The membrane acts like a human kidney. It filters the waste product in the human blood like urea.”

Majari: “Wow.. that’s interesting.. Anyway, can you tell us what is your next article? Maybe you can give us a bit info about it.”
Wahyu: “Hmm… actually in the past 3 days, when I studied for my chemurgy final exam, I read about biohydrogen. I was interested in that topic. So, I will find out all about it, and then write you all fellow readers an article, hehehe.. just wait..”

Majari: “OK, then.. And, last but not least.. What are you going to do with the prize?”
Wahyu: “Well, I will go to a restaurant and spend the money to buy a lot of foods!”

Congratulations, Wahyu! The prize is yours! Happy eating then!

And, is it your turn next? Submit your quality articles and see what others think about you opinion!

Salam Majari Kanayakan.

Share your perspective, get imaginative, and be creative!
Salam Majari Kanayakan.

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And anyway, here is a brief interview with her.

Majari: “Hi, Dinda! You are November’s Author of The Month! How do you feel about that?”
Dinda: “Hi!! Yaa.. of course I’m so happy but actually it’s very surprising!”

Majari: “Great! Anyway, can you tell us in a nutshell what biogas toilets are all about? And how can it stop global warming?”
Dinda: “Well.. biogas toilet is a kind of system that converts human waste into biogas and also fertilizer. And how can it stop global warming? The biogas can be used for electricity or cooking fuel. And we all know that combustion of organic carbon will not will not worsen the global warming. It’s the carbon life-cycle.”

Majari: “Well, global warming is becoming a global issue now. And as we speak, the whole world is having the UN Global Climate Change Meeting in Bali. What do you think about that? Well, Indonesian people should be proud to host a world class meeting like that.”
Dinda: “We have to be proud about this!! That UN Global Climate Change Meeting, held in bali, is hoped to make Indonesian people to be aware about this issue. Don’t only speak out loud about the global warming warning but A REAL CONTRIBUTION is a must.”

Majari: “What do you think, is biogas toilet something that will be feasible to be implemented in our country? Let’s say, rural areas?”
Dinda: “Of course YES.. India can make it feasible.. why can’t we? Some areas in Indonesia are doing this project.”

Majari: “Hmm.. cow and sheep manures are raw materials which usually be converted into biogas. Some areas in Indonesia has been implementing that for 2-3 years. But, what do you think about human faeces?? Will it be something usual in the future?”
Dinda: “Yup.. actually, the biogas from human waste is all the same as biogas from cow and sheep manures.. both can be converted into CH4.. so what’s the different? CH4 is always be CH4..”

Majari: “OK, then.. And, last but not least.. What are you going to do with the prize?”
Dinda: “Buy a dress for myself.. hehe..”

Majari: “Actually, that was the second last but not least. Hehe.. This is the last but not least.. Do you have any messages for the readers? Something to do with global warming, perhaps? The real contribution that you may suggest?”
Dinda: “Hmm.. just show your real contributions to reduce global warming.. It’s started from ourselves. We can drive less and use more fuel-efficient and less-polluting cars. Maybe try to use less electricity and use the energy efficiently. Well, save the energy, save the world!”

Majari: “Thank you for your time, Dinda! Hope to read another interesting articles from you!”
Dinda: “OK.. You’re welcome.. Actually I’m about to publish my article about “Green Burial”. Just keep in touch with Majari. And don’t forget to leave your comments! Hehe..”

Congratulations, Dinda! The prize is yours! Happy shopping then!

And, is it your turn next? Submit your quality articles and see what others think about you opinion!

Salam Majari Kanayakan.

Majari Picks: Web-of-the-Month is Affordabook.com

Bird’s Transport Phenomena

Have you ever thought of buying college books online? Perrys’ Chemical Engineers’ Handbook? Rules of Thumb for Chemical Engineers? Affordabook.com, one of the leading online bookstore on the internet can provide you with all our college needs with a very low price! With an impressive and complete range of catalog, Affordabook.com will give you the right to choose the price and pick the shop where we want to buy the book from!

Remember Bird? He must be somewhere in your mind if you have enrolled the Transport Phenomena subject. Yup, he is the writer of the Transport Phenomena textbook that is widely used in Indonesia. Bird’s Transport Phenomena, the original one of course, will cost us $26.77 ($8.78 shipping price included). Don’t you all know Perry? The one who wrote the ‘Bible’ for Chemical Engineers? The hardcover version of the book will cost us only $95.27 ($5.86 shipping price included). It is quite an investment for college students like us, indeed. But don’t you realize how useful the book is?

See you again later on Majari Picks!
Salam Majari Kanayakan.

Salam Majari Kanayakan.