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Untuk Soal no 1-4 dapat dilihat pada grafik dibawah

Capture1

  1. Sebutkan Proses pada point 3-4
    1. Isobar
    2. Isothermal
    3. Isokhorik
    4. Isentropik
    5. Superheating
  2. Sebutkan proses pada point 4-1
    1. Isobar
    2. Isothermal
    3. Isokhorik
    4. Isentropik
    5. Superheating
  3. Sebutkan proses pada point 1-2
    1. Isobar
    2. Isothermal
    3. Isokhorik
    4. Isentropik
    5. Superheating
  4. Untuk meningkatkan efisiensi pembangkit listrik tenaga uap, terdapat sistem dimana kalor ditambahkan kembali setelah turbin tingkat pertama (high pressure). Apakah nama sistem tersebut
    1. Reheater
    2. Regenerative Close Feed Water Heater
    3. Regenerative Open Feed Water Heater
    4. Expansion valve
    5. Filter dryer
  5. Berikut ini contoh-contoh masalah yang dapat mengurangi performa condenser, kecuali :
    1. Fouling pada pipa kondensor
    2. Kontaminasi dengan air pendinginan (air laut)
    3. Kebocoran pada tube
    4. Korosi pada tube
    5. Pemasangan flow meter untuk menjaga laju masa pendingin
  6. Suatu pembangkit tenaga uap menggunakan batubara untuk sistem pembakaran di boiler. Data dari pengukuran langsung adalah Llaju Aliran main steam : 300 t/h, Enthalpi main steam : 4000 kj/kg, Laju feed water : 250 t/h, Enthalpi feed water : 1120 kj/kg, Laju batu bara : 50 t/h dan GCV : 20000 kj/kg. Berapa nilai efisiensi boiler berdasarkan data pengukuran langsung diatas :
    1. 0%
    2. 5%
    3. 4%
    4. 9%
    5. 3%
  7. Berikut adalah siklus mesin diesel, pada langkah berapa dimana terjadi sistem mendapatkan kalor

Capture2

    1. Langkah 1-2
    2. Langkah 2-3
    3. Langkah 3-4
    4. Langkah 4-5
    5. Langkah 5-1

8. Apakah fungsi dari thermostat pada sistem pendinginan mesin diesel :

  1. Sebagai pembacaan temperatur fluida di sistem pendingin
  2. Sebagai pembacaan laju masa fluida di sistem pendingin
  3. Sebagai kontrol bukaan valve ketika temperatur fluida tinggi
  4. Sebagai pengatur laju massa
  5. Sebagai pengatur aliran fluida berdasarkan temperature fluid

9. Terdapat suatu persitiwa di dalam mesin desel dimana terjadi pembakaran yang tidak merata yang membuat mesin menjadi cepat rusak karena tidak terjadinya keselarasan antara laju kendaraan dengan rpm mesin, peristiwa ini disebut?

  1. Deposit engine
  2. Engine Crack
  3. Overheat
  4. Overhaul Engine
  5. Knocking

10. Suatu mesin diesel untuk pada pengamatan langsung menggunakan tachometer dan neraca pegas. Mesin tersebut bekerja pada torsi 100 Nm dan rpm 120 dengan bahan bakar saat pengukuran sebesar 0.5 kg. Berapa Specific Fuel Consumption mesin tersebut

  1. 50 g/W
  2. 42 g/W
  3. 97 g/W
  4. 39 g/W
  5. 23 g/W

11. Berikut ini fungsi oli pada mesin diesel, kecuali :

  1. Mengatur temperatur mesin
  2. Mengurangi terjadinya gesekan
  3. Mengandung detergen yang lebih baik untuk membersihkan mesin dari kerak
  4. Mengontrol/Mencegah terjadinya endapan karbon pada mesin
  5. Mencegah terjadinya knocking pada mesin
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Galvanic Corrosion

Galvanic corrosion occurs when two different metals have physical or electrical contact with each other and are immersed in a common electrolyte, or when the same metal is exposed to electrolyte with different concentrations. In a galvanic couple, the more active metal (the anode) corrodes at an accelerated rate and the more noble metal (the cathode) corrodes at a retarded rate. When immersed separately, each metal corrodes at its own rate. What type of metal(s) to use is readily determined by following the galvanic series. For example, zinc is often used as a sacrificial anode for steel structures. Galvanic corrosion is of major interest to the marine industry and also anywhere water (containing salts) contacts pipes or metal structures.Factors such as relative size of anode, types of metal, and operating conditions (temperature, humidity, salinity, etc.) affect galvanic corrosion. The surface area ratio of the anode and cathode directly affects the corrosion rates of the materials. Galvanic corrosion is often utilized in sacrificial anodes.Captureoften used as a sacrificial anode for steel structures. Galvanic corrosion is of major interest to the marine industry and also anywhere water (containing salts) contacts pipes or metal structures.Factors such as relative size of anode, types of metal, and operating conditions (temperature, humidity, salinity, etc.) affect galvanic corrosion. The surface area ratio of the anode and cathode directly affects the corrosion rates of the materials. Galvanic corrosion is often utilized in sacrificial anodes.

Pipe Mill Tolerance

Pipe Mill Tolerance in accordance with ASTM, ASME B36.10M is considered to be ±12.5% of the nominal pipe wall thickness, tn. That is to say: if you have a pipe supplied with a nominal thickness tn, and you need to measure the actual thickness, you can find that there is a deviation reaches about ±12.5% tn. I mean, if your pipe with a nominal thickness tn = 10 mm, may be you find the actual thickness is 9 mm or 11 mm, that is mean that there is a tolerance by 1 mm evaluated by ±10%tn, and this tolerance still within the recommended tolerance accepted by the code < 12.5%.This tolerance is applied for all pipes at mill production, even for seamless pipe type (produced without seam welds), i.e. it is a mill tolerance, not related to welding or size of weld bead cap. And this tolerance is given to mill for their insufficient accuracy to produce a pipe wall thickness exactly as the required. And for this reason, we call this pipe wall thickness as the nominal thickness, tn

For Pipe, generally uses Schedule to identify pipe thickness  

For tube, has difference notification, there are AWT (Average wall thickness) and MWT (Minimum wall thickness)

Further detail will be explained later  

Check dP Transmitter

Kendala penggunaan dP transmitter secara umum dan sering adalah kebuntuan, berikut sample visual yang buntu maupun yang tidak

dp

 

Water gauge column sangat penting pada boiler, baik type water tube maupun fire tube. Salah satu clasifikasi yang mengatur adalah ABS maupun LR, DNV, dll

lg

Pada umumnya setiap boiler memiliki minimal 2 yang independen tie in ke drum. Hal ini fungsinya untuk kalibrasi dan memastikan bahwa kedua level gauge dapat bekerja dengan baik. Selain itu, Salah satu harus direct reading gauge glass.

Apa efek apabila 2 level gauge dibuat satu tie in, yaitu apabila error pada koneksi misalnya kotoran maka akan tidak terbaca pada monitor yang dihubungkan di CCTV maupun secara langsung.

Water Gauge biasanya terdapat column dimana terdapat beberapa sensor antara lain dp transmitter maupun electrode yang menjaga agar drum ada air melalui operasional pompa saat operasi kalau tidak akan trip.

Berikut ilustrasi Water Gauge sesuai aturan ABS

lg2

Namun apabila line antara drum dan water gauge pada water line berbeda panjangnya dengan steam line maka akan memberikan deviasi meskipun tidak terlalu besar, bukan karena pressure drop namun volume yang lebih besar karena boundary condition pada water gauge tidak terjadi aliran. sedangkan faktor lain adalah pada water dan steam line telah memasuki fase saturasi artinya sangat sensitif pada temperature, apabila panjang berbeda dengan insulasi yang tidak sama juga maka juga memungkinkan deviasi pembacaan dengan aktual.

lg3

Bagaimana cara membaca digital lavel gauge? yaitu melalui tekanan pada setiap sisi makanya digunakan differential pressure, antara tekanan steam dan water. ketika ada tekanan maka akan dikonversi ke ampere kemudian saat display tinggal disetting. Biasanya saat 0% dan 100%. sehingga kurva berbentuk liner. Namun yang perlu dipertimbangkan adalah ketika bentuk seperti drum tidak dapat liner, kecuali bentuk media seperti box dimana kenaikan setiap level pasti konstan.

Water level sangat penting dalam operasional boiler karena mempengaruhi operasional dan life time boiler. apabila ada kerusakan maka boiler dapat cepat rusak karena kondisi dry dan didalam ada pembakaran. kerusakan tersebut antara lain defleksi maupun kebocoran.

Vendor water level antara lain :

  1. Bont 
  2. Diesse 

 

 

 

 

I realized that we are nothing about knowledge, we are only nano meter even the worst in kilometer of way.

When I worked in Indonesia boiler maker, I got several problem. There are about biomass combustions. Even Indonesia is subject market due to high potential resource but only some researchers want to take care about biomass boiler even Indonesia Research Agency. Short time, I have to check and review paper from Malaysia and so on.

I founded a paper that can answer my queries, after check it’s author beyond researchgate, google scholar and lecture’s profile.

He is amazing research who I ever meet. So I sent me resume and try an opportunity to be his student. Only a half day, he answered my email and fortunately he was in Indonesia so we meet up in Surabaya. He was Prof Hsiao-Kan Ma

After direct discussion and long distance communication, this is it….

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Alhamdulillah I got LOA  from Mechanical Engineering National Taiwan University

But since several conditions that I have to make a priority, I postponed it and still make good communication with Prof HK Ma

Lesson learn is

education is must and continue, it is not only from class but also everywhere. If you got an opportunity takes the class, it is benefit due to structured system in education. Our religion also put attention in education, IQRO

joss

 

 

Cara kerja Cyclone adalah gaya sentrifugal yang diciptakan sehingga membuat massa lebih besar terlempar keluar dan akan mendesak kebawah dimana massa lebih kecil akan terdesak ke tengah dan naik karena tekanan rendah yang tercipta saat berputar

Capture111

Bentuk kerucut akan membantu tingkat separasi dari massa dan ukuran besar saat diujung maka gaya gravitasi akan menangkap ukuran tersebut.

Semakin besar pressure drop yang tercipta maka akan linier dengan tingkat effisiensi penangkapan.

Sangat banyak model cyclone dengan beberapa pendekatan baik dalam memprediksi effisiensi maupun pressure drop dalam bentuk persamaan maupun grafik namun awal pengembangannya harus menggunakan pendekatan kecepatan yang terbagi menjadi tangential, rotation, dan axial velocity hal ini menjadi penting salah satunya untuk menentukan tingkat abrasive yang muncul.

Capture12

Gambar diatas adalah multi cyclone, sepertinya namanya yaitu cyclone dengan jumlah lebih dari 1. Objectivenya adalah meningkatkan effisiensi dengan mendapatkan nilai pressure drop yang rendah.

Untuk inlet tangential dapat menggunakan guide plate, biasanya casting FC20 sedangkan axial inlet mempunyai luas dan rectangular, hal ini tergantung ketersediaan space di project.

Penggunaan cyclone dapat dikategorikan pada solid fuel boiler. karena pada kondisi solid fuel ada games.

Efisiensi cyclone tergantung pada

  • Ukuran partikel

Semakin besar ukuran partikel, maka efisiensi cyclone akan semakin meningkat karena berdasarkan Hukum Stokes, diameter partikel berbanding lurus dengan terminal settling velocity.

  • Diamater dari cyclone

Berdasarkan gaya sentrifugal, diameter cyclone berbanding terbalik dengan gayanya, sehingga semakin kecil diameter cyclone maka semakin besar efisiensinya.

  • Viskositas dari gas

Berdasarkan Hukum Stokes, semakin besar viskositas maka efisiensi cyclone semakin kecil.

  •  Temperatur gas buang

Temperatur gas buang akan mempengaruhi sifat dari fluida.

  • Densitas partikel

Semakin besar densitas partikel maka akan semakin besar efisiensi cyclone.

  • Dust loading

Semakin banyak dust loading maka akan semakin baik efisiensi karena memungkinkan terjadinya tumbukan antar partikel semakin besar.

  • Inlet velocity

Semakin besar inlet velocity maka akan semakin besar efisiensi cyclone.

 

As performance group leader, I have several group interface,they are engineering and project team of main objective, sales and tendering as backup and supporting engineer.

One day, sales guy made a discussion regarding prediction price for next project, I tried make an observation beyond several approx in Internet Data

For below case : Boiler

Target : Astra Agro Lestari

Approach : Making a conclusion from data spreading

a. CPO price : http://www.bappebti.go.id/id/api/harga_bursa.html

b. IDF currency : http://www.bi.go.id/id/moneter/informasi-kurs/transaksi-bi/Default.aspx

c. Stock exchange for AALI  : http://www.duniainvestasi.com/bei/prices/stock

Capture11

Every budgetary already prepared before procurement phase, witch mean if there is unpredictable condition, “limit cost” will be same as it. Since price is market decision, so to make right decision we should make pattern interface between above data and compare with boiler purchasing last period.

Note : Only for company that already listed in stock exchange and if not group company it will differ approach.

Commonly in engineering, every pipe that flow either liquid or gas has to conduct leak test. We divide some responsibilities through leak test.

  • Company shall witness and make punch list activity. They give approval and comment if get any discrepancies.
  • Contractor shall coordinate line check, punch during Leak test from preparation until execution phase. Directly make order to sub-contractor to take action as long as installation of pipe meets the specification.
  • Sub contractor shall execute punch list repair activity, prepare tools to reach close all comments from owner.
  • Vendor, in case we conduct leak test use N2, so vendor has to provide Vessel of N2, hose connection, manifold, pressure indicator, pressure test pump, valve, gas evaporator, filter, fitting, and flushing equipment. Check leakage.

Every pressure must monitor and certified as specification from company.

Before leak test will be conducted, considered things are safety and environment. (crew has to use coverall, safety helmet, glasses, glove, ear plug and portable gas detector). Environment notice about surrounded area may accident in there. so list of chemical spill possibility, source of leaks, and so on. Please consider about blow down valve and do not vent for gas hydrocarbon through atmosphere.

Contractor has to consider about spool and connection and also margin of length. screw of flange! I mind if screw has put cap and another flange and blind flange as portable line stop. different case that i follow tproject. we delete flange on nozzle connection of tank due to flange can’t access if any leakage may occur. and connection has to change with butt weld. Owner did wants to put inside flange in in-deck tank. since the line mention in line list has test pressure but since the line has no pressure (drain), we can carry out leak test with margin length of pipe and weld with blind flange, after it we can delete and make clean the edge of pipe.

Inert Gas Generator, from the name we already known that it is gas to inert on tank. I used this package to prevent explosion on fuel tank. I suppose that Watsilla and Alfa Laval are leading tech on this kind package. As statutory rule and standard, we have to prevent Oxygen contain over 8 % on fuel/oil tank. It is relate with flammable mixture limit. As we know about triangle combustion, vary component such as fuel, oxygen and ignition. A mixture of hydrocarbon gas and air cannot ignite, unless its composition lies within a range of gas-in-air concentrations known as the flammable range. Line A-B that have slope is limit without inert gas, and left line like a curve is line after added inert gas. 

Snap1

Commonly, on offshore project, IGG perform sea water to reduce heat of inert gas after combustion process, and to collect dangerous gas such as NOx and SOx, IGG put Scrubber on top of tank. Fresh water purge wall to prevent corrosion. Before through inside IGG, those fluid will pass on Duplex basket filter, kind of filter that use micro mesh. Fresh air and fuel gas to conduct combustion and nitrogen gas to flash from any accident that may happen. PSV are applied on fresh air and fuel gas to make safety process with set point as by pass from IGG. PV Breaker or pressure vacuum breaker applied on line of gas output. PV Breaker use hydrostatic pressure method.  Kind of safety component to maintain pressure and if it failure inert gas will through out from line by PB Breaker. 

 Schema in IGG (http://marinesite.blogspot.com/2013/06/inert-gas-systemig-systems.html)

Beside preventive on fuel/oil tank explosion, Inert gas can perform to decline condensate oxygen on fuel tank, so that we can ignore condensate that collect on top of tank, then fall and mixture with fuel. Because it can disturb engine combustion  if fuel already contained water. Air on tank has humidity, humidity is water contain in air. During some condition water will adhere on top of tank. and may collect and drop into fuel. 

Please kindly read bellow statutory standard from Canada regarding IGG 

Standard for Inert Gas System – Transports Canada

Before we talk about open drain system, lets discuss first about FPSO and Fix Platform. Since two of kind offshore structure have different on it, but not totally change on concept. Actually, FPSO or Floating Production Storage Offloading is ship that has top side module to process oil from sea bed through riser. Other word, FPSO has characteristic as ship let me say it has trim by default of ship. And Opposite with Fix Platform, Fix platform regardless trim on it’s building. bellow picture is sample of trimmer on ship. 

And what is drain? As we know, drain is line to capture water on deck and will coalesce into header and throw out of ship (if it is just water). But in process system, not only in oil and gas side, drain segregate into 2 kind, Open drain and Close drain. The main different is fluid contain, for open drain may be just water (or little of bit oil contain on water) and pressureless on it. and close drain my be contain oil, water, gas and has pressure. Due to different principle on function, open drain and close drain has different header. Actually, both of  drain have to use slope and it is mandatory. Although close drain has pressure. Even in hazardous and non hazardous area, two of drains have same application. 

From clue issues, open drain has rodding point tundish, open drain box, header, slope. and for close drain without tundish, and open drain box also use rodding point like blind flange for some spot whose advance parameter. 

Let me back application on FPSO and Fix Platform. Slope is how many length of pipe route and will bu down if the number already reached. In math we say gradient, so every slope will have same angle. Slope that capture on P&ID is minimum value. Slope indicate with 100 : 1, 50 : 1, and so on. 100 mm route of pipe, has decrease height 1 mm. Because FPSO has slope, pipe slope on it will different especially the number of slope that opposite position with slope of ship, the number will be bigger, for example by default has 100 : 1, so after we change position, it will be 50 : 1. Different with fix platform, fix platform has typical slope on close or open drain.

Rodding Point : 

Rodding Point has function to clean any blocking on the line. For open drain, rodding point used to drain liquid that trap on deck. Why it has circle of shape? my fooling answer, if we open the cover, and we are careless and wrong place of cover, the cover don’t throw on pipe, because any position of cover can’t make it fall into the header, ignore it. Just joke……

Rodding point on Open Drain

Rodding point on Close Drain

Tundish 

Tundish is piping component to prevent flow, on offshore system, generally, tundish is applied on top of deck and pipe will be higher min 50 mm, slightly like reducer. Tundish can be rodding point, so if any liquid trap on deck we can flow it into tundish.   

Open Drain Box 

Bellow sample of open drain box on street.

And the important of close drain. Close drain prevent any leak from vicinity. it means close drain will connect flange to flange. Especially from process equipment. Any liquid that indicate with free drain on P&ID, if any pocket on routing and we can’t ignore it, after process allow to use pocket, we need to provide drain. It just flange, valve and hose connection. The header on edge used to connect flashing connection, same with drain but on high point of header. So we can purge on that line well if any blocking on it. 

 

Knock Out Drum

Knock Out Drum or KO drum, this equipment is very important through oil and gas system. KO drum used to place before flare system. Slightly this package look like pressure vessel that lay on horizontal position. Main idea on KO drum is gravitation on each fluid into it. Using wall inside as border but not fully close area (like a weir). Let me introduce first regarding KO Drum system. Oil that may contain water, heavy oil, condensate,and gas. Oil will flow into KO Drum to segregate them. Inside KO drum needs heater, and it was provided by hot water form Heating Medium Header. Generally, on FPSO layout, HMH are placed on alone module, but it isn’t far away from Waste Heat Recovery Unit (WHRU). To imaging WHRU, we can look turbocharge on engine, but it will replaced with heat exchanger through outlet gas which output combustion system. Like shell and tube on that connection, but tube is line of exhaust  engine. And shell is small tubes that contain water. After get the heat, water will be used with another packages that need low temperature. Some of them will flow into Heating Medium Heater (HMH). Why we have to use normal water? Actually, we can use water whose normal temperature, but to reach high efficiency, we must use water after absorb heat from WHRU. One of user of those heating water is KO Drum. Actually, if we ignore temperature on line which contain crude oil, it will be big problem for engineer. Since the pipe will block due to wax happen. I already involved on Production Drilling Quarter, in the project indicate that crude oil through KO Drum will be maintain around 40 deg C, even when it is heavy weather. Bellow pic is sample of wax on pipe, please look up bellow link to deeply understand and I got the pic on the link. Let me mention the listening about it, Oil depends on temperature, temperature will effect on viscosity, it means if oil flow with heat tracing on boundary, it will velocity constant. but if it decrease temperature, so average velocity on cross section of pipe will decrease too, and as we know that on edge profile velocity has zero value, so wax layer tend happen on closest of pipe. (WAX LINK)

Oke, back to KO Drum, bellow visualization of KO Drum. Let me try explain bellow figure. After oil inlet in KO Drum, since gravitation, it will separate each others. water will flow on close drain system, oil out after reach a weir inside KO Drum. and gas will out in above nozzle whose Pressure Control Valve to hinder gas entrainment on bellow nozzle (water, oil or both). Some of model use electrostatic on it to coalesce droplet of water into bottom of vessel.

On gas section, before kick from KO Drum, they will allow on mist eliminator. Gas will be routed on many edge to exit from it. The mechanism has many momentum to tend separate water contain. After droplet happened, they will marge and with gravitation,it will drain into vessel again. Mesh parameter can enhance quality of separation.

Sometimes, it will be ambigou if we meet with Slug Cather. Maybe, in my  understanding it has same fundamental, but another purpose. Slug Cather is provide on system (generally on riser system), to hinder slug flow conducted on line. Since it can be big impact if it happen. Slug flow related with water hammer impact. gas expedite velocity above water, and wives continuously can reach top of pipe whose have momentum if impact with elbow, Tee, and so on.

 

 

Alhamdulillah kita masih diberi kesempatan Allah SWT untuk menikmati bulan yang paling mulai dimana pahala berlipat ganda pada tahun ini, ya bulan Ramadhan. Bulang yang paling ditunggu umat muslim. Ada sebuah kisah menarik dari Lauren Booth ketika menjadi pembicara di Makan Malam Tahunan Pendukung Islamic Circle of North America pada 3 April 2011 yang dapat dilihat di youtube. Pada acara tersebut beliau memaparkan pengalamannya ketika hijrah kejalan Allah SWT, Islam, yang diawali dengan perjalanan pembuktian media massa tentang informasi di Palestina karena beliau adalah wartawan di Amerika yang sekarang menjadi aktivis HAM untuk Palestina. Awal yang berat ketika masuk ke Jalur Gaza, Palestina, karena penjagaan yang sangat ketat oleh tentara Israel. Sampai akhirnya beliau “terpenjara” di Jalur Gaza selama 21 hari. Suatu malam beliau berada di pengungsi Rafah dan diundang berbuka puasa saat bulan Ramadhan oleh salah satu keluarga yang sederhana disana, beliau menceritakan bahwa keluarga tersebut sangat sederhana dengan ruang berdinding semen, selembar tikar, 16 alas tidur kumal di dinding untuk 16 anggota keluarga namun sang ibu pemilik rumah menyambut Lauren dengan ramah dan senyum lebar diwajahnya seolah-oleh sang ibu mengajaknya ke istana dan punya segalanya untuk Lauren. Dalam benaknya Lauren sangat marah pada Tuhan umat Islam yang menuntut orang lapar untuk berpuasa. Kemudian Lauren bertanya “Tanpa bermaksud kurang sopan, tapi saya merasa marah melihat kalian berjuang tidak makan,minum sejak subuh sementara yang kaliang miliki begitu sedikit di Gaza, Mengapa Tuhanmu minta kalian puasa di bulan Ramadhan?dia pasti kejam dan tidak waras”. Sang ibu memandang Lauren dengan tidak marah bahkan tersenyum dan menjawab, “Anakku, Allah SWT dan Rosul-Nya meminta kami berpuasa agar ingat orang miskin”. SubhanAllah di kamp pengungsi di Jalur Gaza dalam bulan Ramadhan, mereka berpuasa untuk mengingat orang miskin. Saat itulah hidayah datang dan beliau terharu,tersadar bahkan sampai sekarang  kalau Islam, kasihnya, kemurahannya, kemampuan merasakan kebahagiaan di tengah penderitaan, maka Laurenpun masuk Islam dengan sepenuh hati. Kisah yang menarik untuk menfitrahkan hati kita tentang substansial dan alasan kenapa kita harus berpuasa di bulan Ramadhan. Mari kita persiapkan niat, hati, jasad untuk memaksimalkan Bulan Suci Ramadhan tahun ini seolah-oleh tahun ini kita terakhir kalinya menikmati indhanya sajian Allah SWT di bulan Ramadhan.

Each refrigerant has different properties even same temperature saturation. But sometimes when we use other refrigerant, there is refrigerant has unique properties, may properties change when pressure constant but temperature different. That refrigerant is zeotropic. Generally refrigerant consists of 3 kind refrigerant. The first is pure refrigerant, the second is zeotropic and the last is azeotropic. Pure refrigerant usually consists of at least one fluid, for example R-22, R-134a, and so on. But pure refrigerant has related tightly with other fluid. Different with zeotropic refrigerant. That refrigerant is mixture refrigerant that has composition among liquid and vapor depends on temperature even pressure constant. In contrast, azeotropic may have same content with zeotropic but different composition. azeotropic has unique effect, liquid and vapor strictly change without different composition on pressure constant and a point of temperature.

4

Figure above that alternative refrigerant from Bitzer introduce us about pure refrigerant.

3

Figure above about zeotropic refrigerant and azeotropic in small picture on composition and temperature with pressure constant.

Actually the kinds of refrigerant effect on their thermodynamic properties and heat transfer.  When refrigerant mixture is zeotropic, on pressure constant, value temperature is called gliding temperature. In general saturation temperature is temperature when fluid change of phase, but in here, temperature also changed when phase changed too in along of heat exchanger.

2

__________________________________________________________________________________________

Case Study

__________________________________________________________________________________________

Question

Mol n-butane = 0.6

Mol n-heptane = 0.4

Pressure 700kPa

How many vapor produce from 1 mol as input, if mol butane result 0.8

5

Answer

1 mol consists

0.33 x  mol in liquid + 0.8 x (1-mol inliquid) = 1 mol x 0.6

0.33x + 0.8 – 0.8x = 0.6

0.2 = 0.47 x

x = 0.425 ==> Mol in liquid

Mol in vapor = 1-0.425 = 0.575

Heat exchanger is main equipment in thermal system. As we know, energy is related by heat for any condition. For example power plant with gas turbine. Getting bigger power proportional with higher temperature working in system. Heat affect temperature, when something of spot has different temperature, so that heat flow from higher temperature thought lower temperature. When we produce heat such as from combustion, the problem we must convert that vapor of fluid from liquid condition.  Heat is function of conductivity thermal, different temperature, cross area, thickness, coefficient convective. and if we say convective, other function include on proses such as velocity, fluid, hydraulic diameter, heater, and temperature of fluid.

Heat exchanger can be achieved with two method, the first just different of temperature and the second include changes of phase. In general heat exchanger just with through heat by temperature without change of phase,if any different temperature, it exactly change heat to equilibrium of thermal. And process which include change of phase is called by evaporation and condensation. Evaporation is process to accept heat that makes change of  phase form liquid through vapor and effect form this process is cooling for other fluid because throw heat to evaporate of other fluid. In contrast, condensation is opposite of evaporation that work for throw heat and makes fluid from vapor become liquid.

The benefit if we play phase for heat exchanger because we don’t increase of temperature to get bigger energy through on system. Because that relate with enthalphy of fluid which function of phase and temperature. And process can be better if convection process is high, maybe with enhance pipe with similiar roughness, so that makes fluid be turbulent early enter the pipe.

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Figure above depict temperature of fluid in and out of heat exchanger.  This figure form Fundamentals of Heat and Mass Transfer by Incropere et al. Picture (a) is heat exchanger with condensing vapor to liquid, other fluid increase temperature because accept heat. Picture (b) is heat exchanger with evaporating fluid from liquid through vapor. and picture (c) is normal heat transfer which change temperature to flow of heat.

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Case Study about Heat Exchanger

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Question

How many temperature inlet and outlet for fluid that don’t evaporation

Temperature Evaporator 5oC or278 K

  • Heat of Heat Exchanger 50 kW
  • UA equipment of  exchanger 12 kW/K
  • w.cp from fluid will be cooled 8 kW/K

Answer

Q = w.cp.dT

dT = Q / (w.cp)

To-Ti = -50/8 = -6.25                       Equation I

negative value is direction of heat that is absorbed by evaporator and it is mean other fluid is cooled (Ti > To)

To-Ti = (Te-Ti)(1-e^(-UA/(w.cp)))

To-Ti = (278-Ti)(1-e^(-12/(8)))

To-0.22Ti=216.84                               Equation II

Elimination of Equation I and II

To-Ti = -6.25

To-0.22Ti=216.84

—————————-

Ti = 13.01 C

To = 6.76 C

So that, in cooling process uses heat exchanger with evaporation process as cooling media get temperature inlet around 13.01 C and outlet 6.76 C, and constrain temperature evaporator is 5 C

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Question

t1,o = to = ?

q = 500 W/m2

h1 = 45 W/m2.K, h2 = 12 W/m2.K

A = 1m . x = x (m)

t1,i = ti = ambient temperature = 15oC

w = 0,02 kg/s, cp = 1000 J/(kg.K)

Answer

to = ti + (tc – ti)(1 – e-UA/wcp)

Δtc = q/U = 500/9,47 = 52,8oC

tc = 52,8 +15 = 67,8oC

So that, to = 15 + (67,8 – 15)(1 – e-9,47.x/0,02.1000)

to = 15 + 52,8 (1 – e-x/2,11)

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