#Dis-Advantages of Air Cooling System in IC Engine

[starr-fall-knight-rise]

Humans are Space Orcs: The Marathon

From the Intergalactic Journal of Mechanics and Biology

They say that a single human once ran for 80 hours 44 minutes without stopping to sleep. He covered a distance of 350m (360km) during that time. At a relative speed of less than 5 miles an hour, the speed pales in comparison to other apex predators of their planet. The spotted cheetah can run up to 76 miles per hour, but can only sustain that for approximately 1,500 feet. The best bread and trained horses of their planet may be able to run 100 miles in a day, but many who attempt this feat never finish.

Despite its relative speed, the human can sustain a relative pace of four miles an hour four a little over three earth solar cycles without rest (keep in mind that this is not an examination of average ability).

Once thought to be the most endurance evolved species in the galaxy, the Rundi can run for an hour at the speed of fifteen miles per hour, but in a long distance race with a human, they find themselves slowly outmatched.

First, they outpace the human easily, they grow slowly tired, they fall to a slow walking speed, they try to maintain, but their body overheats. Eventually the steady footsteps of the approaching human converge and then pass ahead to recede into the distance.

Compared to most creatures, the human has a few advantages. Bipedal in nature, they can carry objects with them as they run like water and food, the arches in their feet act as shocks and springs to decrease shock. The feet are oriented straight ahead and their toes are shortened to decrease the mechanical work of the foot. Spring-like tendons and ligaments aid them as they run. A narrow waist that can pivot allows for the swimming of arms during running action. A heightened sense of balance and movement keeps them on a straight course and allows their head to remain steady as they go. About 20 miles of energy can be stored in the muscles themselves. Additionally, one of the largest muscles in the body, the gluteus maximus is not engaged during a brisk walk but during a run. But the biggest factor, is their ability to cool through sweat.

As far as we know, humans, and some of their earthly counterparts, are the only creatures in the universe that excrete water to catalyze cooling.

 They were going to die.

They were going to die.

The sun would come up, and burn them to death and they were going to die.

Krill never thought that his life would end this way. Surrounded by the strange Humans on a class A death planet waiting for the star to rise over the horizon and melt them to a crisp.

Even the humans standing in the desert sand around him looked subdued. Usually, during near death situations, they were relatively chipper, but this was different. They knew they were going to die.

Captain Vir gave a sigh, “Knew we shouldn’t have trusted that little scab.” He muttered looking up towards the sky where the troop transport had vanished carrying with it their merchandise and its conniving Tesraki pilot probably laughing gleefully to himself about the stupidly of the trustingly naive humans.

The darkness was so profound out in the desert at night, though the stars overhead were particularly striking.

Krill, the captain asked, “How far are we from the sanctuary.”

A few quick calculations in his head and Krill felt himself sink towards the sand. This was hopeless, and the planet’s magnetic field made their communications ability almost nonexistent.

“How far?” The captain prodded

“40 Units.”

“In miles please, America still hasn’t switched to the metric system.”

A quick calculation

“25 miles.”

A sudden shift in the group, and he looked up to find a confusing sight. The humans looked almost hopeful glancing around at each other.

The captain grinned, “That’s great news.”

Krill stared at him in disbelief, “25 MILES captain. And only seven hours before the sun comes up. We have no chance.”

A bark of laughter escaped the humans.

A cheer rose up.

What was happening?

“Anyone here ever run a Marathon?” The captain asked

The human’s cheering died down and there was a pause.

The captain frowned, “Anyone want to run for their first time?” He questioned

Silence.

Krill stared on in confusion, “I’m sorry, what is a Marathon.”

“It’s sort of this tradition we have. Supposedly after the final battle between the Athenians and the Persians, an Athenian soldier ran 25 miles back to Athens to tell of the victory before he died.”

Krill blinked in horror, “A tradition.”

“Yeah, they hold them all the time back home.”

“So a few of you just give up your lives to run a race.”

Laughter shook the sand around him.

“No, thousands of people come to participate, and no one usually dies. Most people are up and walking after about an hour or two if not directly after.”

Krill stared at the humans in a mixture of awe.

The captain rubbed the back of his neck, “I suppose I could do it.

“Yeah send the one eyed one leg cripple to run for our lives.” One of the humans commented sarcastically

“I could go.” Another volunteered

The captain shook his head, “I may have one leg, but that just means I can’t feel pain in it. Not to mention I used to run when I was younger.”

“Used to being the key point there.” Someone muttered

“I heard that.” The captain snapped though there was less malice in his voice than one might have supposed.

Krill sometimes did wonder about that. In most species cultures, the crippled were weeded out in order to preserve the race, but these humans were odd. Losing a limb seemed to have the opposite effect, and if you could function with a missing limb, the humans were even more impressed.

He wondered if it wasn’t some sort of primitive form of dominance. The more scars you had the more fights you had survived, which made you the strongest.

The captain dropped his bag to the ground and began pulling off his jacket. Krill shook his head, “Captain, it is too cold out.”

The captain shook his head, “I’ll warm up.” Krill stared on in confused fascination as the man proceeded to strip off his outer layer until he stood in nothing but his undershorts and socks.

The other humans laughed and cat called back to their normal oblivious selves.

Did they not understand how dead they were? They were alone waiting for sunrise on a class A death planet. This was no time to be laughing at partial nudity.

The captain struck some sort of pose earing jeers before motioning to one of the other men, “Your shoes.”

“But captain, I.”

“Shoes, lieutenant, I am not running 26 miles in combat boots.

Reluctantly the other man gave up his shoes and handed them to the other man.

The group grew quiet, and began pulling out supplies putting together a small bag of water and food.

The captain stood on the outskirts of the group stretching his flesh leg before checking the functioning of the robotic one. Both seemed to be working seamlessly.

His teeth shattered, and he began hopping around in a circle.

The man really had gone mad.

The lieutenant with the missing shoes approached him from the side, “You better hurry captain. I set a watch for you. You should have Seven hours to make it, but it will get hotter as the sun approaches.” The Captain nodded, and with a sort of surreal optimism, he began his run letting off a whoop into the night as if he was challenging he sun itself.

Humans were reckless like that. They believed they could beat anything.

It was an almost beautiful thing to watch as the human grew smaller and smaller against the horizon. His footing was sure and seamless despite his injury. As a medic, Krill could almost see the cords of muscle contracting and lengthening under the skin. Despite its awkward appearance, the human really was graceful when in his element.

***

He wasn’t’ thinking that four hours later when the sky began to lighten. It was barely perceptible but he could feel it, and he could feel the heat of the approaching sun already beginning to warm him. The humans could feel it too, and they began taking off their jackets looking towards the horizon where their doom was fast approaching.

The jokes were sparser now as were the smiles. He could sense the tension on them as hormones in the air. Adrenaline…. The scent of the poison made him ill, and he had no idea how the humans survived straight injections of it into their system.

The sky grew brighter. The heat was at around 70 degrees now.

The humans appeared comfortable, and so was he, but anything above 75 and he would begin to wilt. The humans told him they could withstand temperatures up to 100+ degrees for short periods, and not very comfortably.

He could tell when the heat increased because he felt his body shutting down.

In an act of reckless and pointless kindness, the humans used the rest of their remaining water to cool him. Not like it would matter. They were dead anyway.

Hour five rolled by, and he was sure they were dead…. He was fading quickly as the heat grew to around 80 degrees. The humans frantically fanned him from all sides. In a sort of delirious haze he felt a sense of attachment to these strange creatures who had taken him in despite the divide between species.

That’s when they heard the sounds of the engines.

Looking up into the sky they caught sight of the transport fast approaching, and a great cheer rose into the air. He couldn’t believe it.

It took a few minutes at 90 degrees before the ship landed, and he was quickly carried inside by a mass of cheering humans, door shutting behind them with a screech.

He was enveloped in cool bliss. Enough to finally lift his head and look around annoyed that the humans seemed relatively fine despite sheen of sweat and a few headaches, and of course…. The captain.

He sat hunched under a reflective emergency blanket with an ice pack to his head. His prosthetic leg was gone and his other foot was a mass of blisters. His upper legs were a mass of raw skin where friction had rubbed it away, but he was grinning.

He must have seen the awed look on Krill’s face for he gave a wink, “Told you, easy. We humans do it all the time.”

Krill shook his head in amazement and fascination. They really were indestructible.

Of course, he may not have thought that later on if he had watched the captain limp piteously back to his room, squeal like a girl when the shower water touched his chafed skin all before flopping into bed to sleep a continuous thirteen hours.

That part would be conspicuously missing from the story. A story that told of a one-legged one-eyed human who ran 26 miles in almost no clothes during heat ranging from 40-90 degrees on a class A death planet under six hours all to save his crew.

[changingourdestiny]

Beyond Light Part 5: Stasis, Secrets & Science

Summary:

Rae and friends travel beneath the ice to Bray Exoscience to locate the next shard and Praksis. But they end up learning something else regarding one of their own members...

Previous Part: Here

Next Part: Here

“To my Eliksni sisters and brothers out amongst the stars and here at home on Europa: we have suffered a great loss today. Our beloved warrior Phylaks was murdered by not only a pawn of the once ‘Great Machine’, but a human Captain of the traitors known as House Light. As always, the machine-spawns eagerly seek to eradicate us. Remember, Light only burns bright for so long, but Darkness is forever.”

 “Traitors? Like she has room to talk!”

Tif pouted as Fireteam Paralight made their way their way down through the ice towards Bray Exoscience where the pull of the next shard was leading them. “Don’t mind her.” Blaze grinned, giving the Titan a playful nudge, “She’s just salty that we beat her best warrior. If she has a problem, she can shove it up her- whoa.”

Blaze cut herself off as they entered the inside of the facility. Despite being around for centuries and buried in ice, the inside was near spotless…aside from the dark shard floating above the platform. “Ok, I still stand by the fact that Clovis is a piece of crap,” Blaze began as she looked around, “But this place looks really nice.”

“Yeah! So shiny!” Tif beamed. Rae and Marcia approached the platform where the shard was. “You mind if I go this time?” Marcia asked, “I’ve had experience with Darkness before and I wanna ensure this doesn’t have any effects on Starlight.”

“Be my guest.” Rae motioned to the shard as she stepped back, allowing Marcia to double jump onto the platform. The Nightstalker took out her splinter and walked up to the shard, holding it up like Tif did. There was a brief glow as Marcia felt herself being frozen in stasis. She closed her eyes and let it happen. As the last of her was frozen, Rae watched as Marcia suddenly burst out of the stasis with a strained yell as what seemed to be two kama blades appeared in her hands. “Whoa!” Marcia exclaimed, examining the blades, “Not bad. Not bad at all!”

“Marcia, Eliksni incoming!” Nox alerted as Marcia spotted Fallen entering from a door at the other end of the room. “Good.” Marcia smirked, “Let’s see what this power can do!” Marcia leapt up into the air and threw her first blade at a group of Fallen, freezing them in place, as the second one exploded on impact and formed a stasis form that hunted down the remaining Fallen. “Whoohoohoo!” Marcia whooped, “This is so much better than Void!” The Hunter summoned what seemed like a stasis shuriken and threw it at a group of shanks. It ricocheted off each of them, striking all of them down. Marcia landed on the ground, rolling in the process, before snapping her fingers, letting out a wave of stasis. It went straight towards a servitor, freezing it in place, before seeking out the surrounding Fallen. Marcia whipped out her rocket launcher, Bad Omens, and fired it at the frozen Fallen, shattering them into pieces. Marcia sighed with a content smirk before feeling the energy leave her once more.

  “Now that!” Marcia grinned, stretching, “That felt satisfying!”

“Marcia, that was awesome!” Tif cheered. “Man…you took out those Eliksni like it was nothing.” Blaze mused, impressed.

“Well, now that that’s taken care of,” Rae began, “I’m gonna take a look around before we head back.”

“Why? There’s not much here. Well, aside from the Exo bodies. Which are very disturbing, might I add?” Blaze asked as she cautiously walked around a robotic body that was laying on the ground. “Eramis isn’t stupid.” Rae replied, sitting at a computer, “There’s no way she wouldn’t use the remaining tech here to her advantage. Chances are we might find something of use here.”

“Knock yourself out.” Marcia shrugged as she sat on the edge of the platform, her legs dangling. Rae browsed through the remaining files on the computer. A few of them were corrupted beyond salvaging, some were just cat pictures. Her curiosity was peaked when she saw a file with the lists of faculty members for each CB site in the system, one of them being Site-6. “Hey there’s a list of staff members for Site-6 here.” Rae called to Blaze. “Cool! We get to know who the assholes were that made SIVA.” Blaze chuckled, leaning over Rae’s shoulder to look at the list as Rae scrolled through it, “Screw you, Dr. Escher Zhang. Screw you, Dr. Marnie Ziglar. Screw you especially, Dr. Wilhelmina Bray. Screw you, Dr. A-”

Blaze went silent. Rae stopped scrolling.

“Uh…you guys okay?” Tif asked from where she was sitting beside Marcia. The two were just staring in disbelief at the screen. Marcia raised an eyebrow before hopping off the platform and walking towards them, “What’s got you two so rattled?” She peered over their shoulders at the screen and her face dropped in realisation, “Oh…”

Dr. Adam Bergfalk.

“It…it can’t be, right?” Blaze chuckled nervously, “There’s…gotta be loads of people with that name.”

“Only one way to find out.” Rae muttered as the clicked the file.

 Name: Dr. Adam Bergfalk.

Age: 36.

Rank: Junior Engineer for SIVA Project.

Assigned to: SIVA Replication Complex Site-6.

Important Notes:

Please ensure Dr. Bergfalk remembers to bring is arm in for weekly maintenance and himself for weekly check-ups. Ensure SIVA has affected no other parts of his body. We don’t need it eating his head too. We need that. ~SIVA.MEM.WB

Dr. Bray, as I’ve said a million times, my arm is FINE. I appreciate the check-ups, but I would also appreciate a little more confidence in my handywork. Speaking of which, whoever graffitied my arm with permanent marker while I was asleep: jokes on you, dumhuvud! I always have a spare on hand. And no, that’s not a pun. Also, I’ll be speaking to HR about some of the ‘statements’ you wrote. ~SIVA.MEM.AB

 In the corner of the profile was a mugshot of Adam. He had a confident and determined smirk on his face – almost a contrast to the quiet yet friendly Titan Rae and Blaze knew for so long. “Adam worked for Clovis…” Rae muttered. “Does it mention anything else?” Blaze asked, “Maybe he saw what assholes they were and quit?” Rae scrolled down through the file which had research notes, information and pictures in it, some of which were pictures of him with several other scientists when he first joined, one was him in a hospital bed without his arm looking very fed up while someone who bared resemblance to him seemed to be berating him, another was of him with a wrench in his mouth while he used a screwdriver to work on his metal arm which looked different to his current one – Rae assumed this arm was a prototype. Finally, Rae came across a note at the bottom.

 NOTICE OF MIA:

Following an explosion is his lab at Site-6, Dr. Adam Bergfalk has been reported as MIA as no trace of his body has been found. Until further notice, position of Junior Engineer has been passed to his assistant, Dr. Sigfrid Bergfalk. Investigation into the accident is underway and any new information will be posted here.

 “My guess is he died in that explosion…but they didn’t find his body?” Blaze spoke. “Maybe he managed to get out after the blast but died somewhere else?” Marcia suggested.

“I can’t believe it…” Rae muttered.

“Me neither.” Blaze replied, “To think he worked on-”

“He looks so smug!” Rae laughed, catching the other two Hunters off guard, “He’d never smirk like that now. He must’ve been a pain to work with. He sounds so sassy in his notes too!”

Rae got up from where she was sitting and turned off the computer, “Well, we better get back to work. Let’s head back to Variks’s place and figure out our next move.”

“You’re…not freaked out that Adam worked for the Brays? On Siva?” Blaze asked, confused. “Why would I be?” Rae replied with a smile, “That Adam died ages ago. He’s definitely not the Adam we know now. It doesn’t matter who he was, it’s who he is now.”

Blaze seemed surprised, her voice leaving her. “Hey!” Tif called over to the trio, “I just got a message from Variks! He says our next target is somewhere here in the facility!”

“C’mon, we got a house to tear down.” Rae smiled as she got her gun at the ready and continued into the labs. “Who he is now…” Blaze muttered as she subconsciously reached to where her ring once hung around her neck before smiling and following Rae alongside Tif and Marcia, feeling reassured.

“Brig incoming!”

“TRAVELLER’S CRACK!!!”

 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 “I have seen what power has done to Eramis. But…perhaps you are different. Perhaps there is hope. Praksis. He is the visionary mind behind Eramis’s technology. He wrings power from the Darkness itself. But Variks was not privy to his secrets, his experiments. You must discover how he creates these dark weapons…and stop him.”

 “I…hate…BRIGS!” Blaze growled as she tried to catch her breath, the remains of the giant brig smouldering on the platform. “No, no, no…” Praksis’s voice came through the comms, “Troubling. Embarrassing. I must keep this from Eramis. The data must be clean.”

“D’aww! Is he embawwassed that the wittle Guardians twashed his science pwoject?” Marcia cooed before laughing. “Yeah, antagonise the Eliksni in charge of Eramis’s weapons. That’ll end well.” Rae sighed. “Relax! We’ll be fine! Let’s go!” Marcia took off towards the entrance at the back of the room when…

*BA-BOOM!!!*

“Guardian down.” Nox announced as Marcia’s body was thrown across the room by the explosion, “There were tripwires.”

Praksis could be heard laughing through the comms as Nox revived Marcia who then got to her feet. Rae started laughing, “Now you can’t give me slack for the time I triggered Drifter’s tripwires when you fell for the same trap!”

“Yeah, yeah.” Marcia groaned as she stretched, “Let’s just go kill Eramis’s head nerd already.”

 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 “We should be nearly there.” Rae called out as the fireteam traversed the halls of Bray Exoscience.

“Hang on! I’m almost there!”

Rae, Blaze and Marcia turned around to see Tif slowly approaching them on what seemed like a roomba – similar to the ones Rae saw on Titan. “Really?” Marcia smirked, raising an eyebrow. “What? They’re cool!” Tif grinned, “And strong. I’m wearing a good bit of armour and this can still carry my weight no problem.”

“Well, you are pretty small.” Marcia chuckled.

“Am not! I’m 5 ft 6!” Tif pouted, “I’m not that much smaller than you!”

Marcia laughed, “I’m just messin’ with ya, Tif.”

Tif stuck out their tongue before hopping off the roomba and following the others further down the hall.

“Hey, Rae?” Tif asked.

“Yep?”

“I’ve been meaning to ask, since you and Variks mentioned him before, but who’s Cayde-6? He’s an Exo, right?”

Rae nodded, “He’s the Hunter vanguard and my boyfriend. He and his Ghost died in the Prison of Elders, but I was able to save him with an ability Paralians have.”

“Awesome!” Tif beamed, “My girlfriend’s a Hunter too. She’s super cool!”

“Wait. You have a girlfriend?” Blaze asked, seeming surprised. “Yup!” Tif replied happily, “Her name’s Azara. But I call her Azzy and she calls me Tiffy! She looks scary and mean but she’s super nice and cool! She likes being in the wild and sometimes visits me at Misraaks’s skiff when she’s passing through. One time, I was about to get blasted by an ogre and she picked me up and saved be before I got exploded. She’s really strong and she’s so fast! It felt like we teleported when she saved me. I love her so much!”

Rae couldn’t help but smile as Tif talked about their girlfriend. Their eyes were practically twinkling, and the smile never left their face. “You two must love each other very much.” Blaze noted. “Of course!” Tif grinned, “I’d do anything for her, and she’d do anything for me too! Right now she’s in the Tangled Shore investigating some Eliksni that were acting weird. I’ll be joining her once I finish up here.”

“Well, let us know if you ever need backup. We’d love to meet her.” Rae smiled.

“I will! She’d love to meet you too!”

 The fireteam arrived in a large room with a catwalk leading to an odd, spherical object. As they approached the catwalk, Praksis’s laugh cut them off as he came flying in on a Shank that exploded as he landed before them. “Well that was an entrance.” Rae muttered. “Eramis does not permit errors, so I will not fail.” Praksis growled as he got is gun at the ready. “What a coincidence!” Marcia gave a dark grin as she activated her super, a void bow appearing in her hands.

“Neither do I.”

 To Be Continued…

[mechanicalstudents-blog]

Cooling System in IC Engine: Water Cooling systems,types, Air Cooling Systems,Adv,Disadv

Cooling System in IC Engine-Water Cooling systems and Air Cooling Systems, Advantages, Dis advantages:As per the engines, the heat produced by the combustion of fuel in the engine cylinder is not converted into useful power at the crankshaft completely and the typical distribution of fuel energy is as follows.

Useful work at the crankshaft = 25 %

Loss in exhaust gases= 35 %

Loss to the cylinders…

[siva3155]

100+ TOP THERMAL Engineering VIVA Questions and Answers

THERMAL Engineering VIVA Questions :-

1. Define heat transfer? Heat transfer can be defined as the transmission of energy from one region to another due to temperature difference. 2. What are the modes of heat transfer? Conduction Convection Radiation. 3. What is conduction? Heat conduction is a mechanism of heat transfer from a region of high temperature to a region of low temperature within a medium or different medium in direct physical contact. 4. State Fourier’s law of conduction. The rate of heat conduction is proportional to the area measured normal to the direction of heat flow and to the temperature gradient in that direction. Q α – A dT / dx Q = -kA dT /dx Where, A – Area in m2 . dT / dx – Temperature gradient, K/m k – Thermal conductivity, W/mK. 5. Define Thermal conductivity. Thermal conductivity is defined as the ability of a substance to conduct heat. 6. Write down the equation for conduction of heat through a slab or plane wall. Heat transfer, Q = ∆ Toverall / R Where, ∆ T = T1 – T2 R = L / kA – Thermal resistance of slab L – Thickness of slab K – Thermal conductivity of slab A – Area 7. What are the factors affecting the thermal conductivity? Moisture b. Density of material c. Pressure Temperature e. Structure of material. 8. What is meant by free or natural convection? It is fluid motion is produced due to change in density resulting from temperature gradients, the mode of heat transfer is said to be free or natural convection. 9. Define Grashof number . It is defined as the ratio of product of inertia force and buoyancy force to the square of viscous force. Gr = Inertia force x Buoyancy force / 2 10. Define Stanton number . It is the ratio of Nusselt number to the product of Reynolds number and Prandtl number. St = Nu / Re x Pr. 11. What is meant by Newtonion and non-newtonion fluids? The fluids which obey the Newton’s law of viscosity are called Newtonion fluids and those which do not obey are called no-newtonion fluids. 12. What is meant by laminar flow ? Laminar flow: Laminar flow is sometimes called stream line flow. In this type of flow, the fluid moves in layers and each fluid particle follows a smooth continuous path. The fluid particles in each layer remain in an orderly sequence without mixing with each other. 13. Define Convection. Convection is a process of heat transfer that will occur between a solid surface and a fluid medium when they are at different temperatures. 14. Define Reynolds number . It is defined as the ratio of inertia force to viscous force. Re = Inertia force / Viscous force 15. Define Prandtl number . It is the ratio of the momentum diffusivity to the thermal diffusivity. Pr = Momentum diffusivity / Thermal diffusivity 16. Define Nusselt Number . It is defined as the ratio of the heat flow by convection process under an unit temperature gradient to the heat flow rate by conduction under an unit temperature gradient through a stationary thickness of metre. Nusselt Number = qconv /qcond 17. State Newton’s law of convection. Heat transfer from the moving fluid to solid surface is given by the equation. Q = h A = This equation is referred to as Newton’s law of cooling. Where h = Local heat transfer coefficient in W/m2K. A = Surface area in m2 . Tw = Surface Wall temperature in K. T∞ = Temperature of fluid in K. 18. What is forced convection? If the fluid motion is artificially created by means of an external force like a blower or fan, that type of heat transfer is known as forced convection. 19. What are the dimensionless parameters used in forced convection? Reynolds number . Nusselt number . Prandtl number . 20. Mention Stefan boltzman contant. σ = Stefan Boltzman constant = 5.6697 x 10-8 W/ (m² K4) 21. Define Stefan boltzman contant. Stefan Boltzman law states that the total emissive power of a perfect black body is proportional to fourth power of the absolute temperature of black body surface Eb = σT 4 σ = Stefan Boltzman constant = 5.6697 x 10-8 W/ (m² K4) 22. Define Emissive power . The emissive power is defined as the total amount of radiation emitted by a body per unit time and unit area. It is expressed in W/m2 23. Define monochromatic emissive power. The energy emitted by the surface at a given length per unit time per unit area in all directions is known as monochromatic emissive power. 24. What is meant by absorptivity? Absorptivity is defined as the ratio between radiation absorbed and incident radiation. Absorptivity, α = Radiation absorbed / Incident radiation. 25. Define Radiation. The heat transfer from one body to another without any transmitting medium is known as radiation. It is an electromagnetic wave phenomenon. 26. Define Emissivity. It is defined as the ability of the surface of a body to radiate heat. It is also defined as the ratio of emissive power of any body to the emissive power of a black body of equal temperature. Emissivity, ε = E / Eb. 27. Define Emissive power . The emissive power is defined as the total amount of radiation emitted by a body per unit time and unit area. It is expressed in W/m2. 28. Define monochromatic emissive power. The energy emitted by the surface at a given length per unit time per unit area in all directions is known as monochromatic emissive power. 29. What is meant by absorptivity? Absorptivity is defined as the ratio between radiation absorbed and incident radiation. Absorptivity, α = Radiation absorbed / Incident radiation. 30. What is meant by reflectivity? Reflectivity is defined as the ratio of radiation reflected to the incident radiation. Reflectivity, ρ = Radiation reflected / Incident radiation. 31. What is meant by transmissivity? Transmissivity is defined as the ratio of radiation transmitted to the incident radiation. Transmissivity, τ = Radiation transmitted / Incident radiation. 32. What is black body? Black body is an ideal surface having the following properties. A black body absorbs all incident radiation, regardless of wav e length and direction. For a prescribed temperature and wave length, no surface can emit more energy than black body. 33. What is meant by gray body? If a body absorbs a definite percentage of incident radiation irrespective of their wave length, the body is known as gray body. The emissive power of a gray body is always less than that of the black body. 34. What is heat exchanger? A heat exchanger is defined as an equipment which transfers the heat from a hot fluid to a cold fluid. 35. What is meant by Direct heat exchanger open heat exchanger? In direct contact heat exchanger, the heat exchange takes place by direct mixing of hot and cold fluids. 36. What is meant by Indirect contact heat exchanger? In this type of heat exchangers, the transfer of heat between two fluids could be carried out by transmission through a wall which separates the two fluids. 37. What is meant by parallel flow heat exchanger? In this type of heat exchanger, hot and cold fluids move in the same direction. 38. What is meant by counter flow heat exchanger? In this type of heat exchanger, hot and cold fluids move in parallel but opposite directions. 39. What is meant by cross flow heat exchanger? In this type of heat exchanger, hot and cold fluids move at right angles to each other. 40. What is meant by Shell and tube heat exchanger? In this type of heat exchanger, one of the fluids moves through a bundle of tubes enclosed by a shell. The other fluid is forced through the shell and it movesover the outside surface of the tubes. 41. What is meant by LMTD? We know that the temperature difference between the hot and cold fluids in the heat exchanger varies from point to point. In addition various modes of heat transfer are involved. Therefore based on concept of appropriate mean temperature difference, also called logarithmic mean temperature difference, the total heat transfer rate in the heat exchanger is expressed as Q = U A m Where, U=Overall heat transfer co-efficient , A=Area, m2 m = Logarithmic mean temperature difference. 42. What is meant by Effectiveness? The heat exchanger effectiveness is defined as the ratio of actual heat transferto the maximum possible heat transfer. Effectiveness ε = Actual heat transfer / Maximum possible heat transfer = Q / Qmax 43. Power requirement of a refrigerator is___________. Inversely proportional to COP. 44. In SI units, one ton of refrigeration is equal to _________. 210 kJ/min. 45. Define tons of refrigeration and COP. A tonne of refrigeration is defined as the quantity of heat required to beremoved from one tonne of water at 00C to convert that into ice at 00C in24 hours. In actual practice,1 tonne of refrigeration = 210kJ/min = 3.5kW. 46. The capacity of a domestic refrigerator is in the range of ___________. 1 to 3 tonne. 47. Name four important properties of a good refrigerant. Low boiling point. High critical temperature & pressure. Low specific heat of liquid. 48. What is the difference between air conditioning and refrigeration? Refrigeration is the process of providing and maintaining the temperature in space below atmospheric temperature. Air conditioning is the process of supplying sufficient volume of clean aircontaining a specific amount of water vapour and maintaining the predeterminedatmospheric condition with in a selected enclosure. 49. Name any four commonly used refrigerants. 1. Ammonia . 2. Carbon dioxide . 3. Sulphur di oxide . 4. Freon – 12. Dr. N.N.C.E MECH/ VI Sem TE LAB II - LM52 50. What are the advantages and disadvantages of air refrigeration system? Advantages: 1. The refrigerant used namely air is cheap and easily available. 2. There is no danger of fire or toxic effects due to leakages. 3. The weight to tonne of refrigeration ratio is less as compared to other systems. Disadvantages: 1. The quantity of refrigerant used per tonne of refrigeration is high as compared to other system. 2. The COP of the system is very low. Therefore running cost is high. 3. The danger of frosting at the expander valves is more as the air contains moisture content. 51. What is net refrigerating effect of the refrigerant? Refrigerating effect is the total heat removed from the refrigerant in the evaporator. COP = Refrigeration effect / Work done. Refrigeration effect = COP x Work done. 52. Define refrigerant. Any substance capable of absorbing heat from another required substance canbe used as refrigerant. Read the full article

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IC Engines-Cooling Systems,Types, Performance Parameters, Lubrication of IC Engines

IC Engines-Cooling Systems,Types, Performance Parameters, Lubrication of IC Engines

IC Engines-Cooling Systems, Types, Performance Parameters, Lubrication of IC Engines: Already, I had discussed Classification of IC Engines-Types of Heat Engines, Basic Engine Components & IC Engine Nomenclature in a detailed way. Apart from that, if you want to know about SI Engine, CI Engine, Otto Cycle, Diesel Cycle, Carnot cycle, you can click on the links provided. Here, in this article, I…