Phid 412 (Self-assessment For Quiz 1) . Kats

The statement is stating that heat sources can be either directly or indirectly, meaning that heat can be generated either directly from the source or indirectly through a medium. This is a true statement as heat can be produced through various means such as burning fuel directly or through the use of heating systems that transfer heat indirectly through convection or radiation.

The given equation A∆T/(B/X) is not true. The correct answer is False.

Ammonia gas has the highest latent heat among common refrigerants. This means that it requires the highest amount of energy to change its state from a gas to a liquid, and vice versa. This property makes it an efficient refrigerant as it can absorb and release a significant amount of heat during the refrigeration cycle. Other common refrigerants such as R-134a or R-410a have lower latent heats compared to ammonia. Therefore, the statement "Ammonia gas has the highest latent heat among common refrigerants" is true.

Brine is a concentrated salt solution because it is made by dissolving a large amount of salt in water. This results in a solution with a high concentration of salt, which is commonly used for pickling and preserving food.

Mechanical stem traps are designed to handle high condensate loads and are more efficient in draining large amounts of condensate compared to thermo static traps. This is because mechanical stem traps use a float and lever mechanism to open and close the valve, allowing for better control and drainage of condensate. Thermo static traps, on the other hand, rely on the difference in temperature between the condensate and steam to open and close the valve, making them less effective in handling high condensate loads. Therefore, the statement is true.

The statement "A 1:1 heat exchanger is affixed head heat exchanger" is false. A 1:1 heat exchanger refers to a heat exchanger where the heat transfer is equal on both the hot and cold sides. On the other hand, an affixed head heat exchanger is a type of heat exchanger where the shell is fixed and the tube bundle can be removed. These are two different types of heat exchangers, so the statement is incorrect.

The statement is true because specific heat refers to the amount of heat energy required to raise the temperature of a given substance by a certain amount. It is defined as the heat energy required to raise the temperature of one unit mass of a substance by one degree. Therefore, the given statement accurately describes the concept of specific heat.

The statement "H is expressed in btu/hr-ft-f (k) ft2" is false. The given expression is not a valid unit of measurement. It is likely a combination of different units or a typographical error. Therefore, the correct answer is false.

The equation provided is not mathematically correct. It seems to be an attempt to calculate a value for "u" using variables "nAl", "KA", and "mA". However, the equation is missing some necessary mathematical operations and parentheses. Therefore, the correct answer is False, as the equation is not valid.

Horizontal tube evaporators are not preferred over vertical tube evaporators. In fact, vertical tube evaporators are generally preferred in many applications. Vertical tube evaporators have several advantages such as better heat transfer efficiency, easier cleaning and maintenance, and smaller footprint. They also allow for better separation of the vapor and liquid phases, resulting in higher quality product. Horizontal tube evaporators, on the other hand, are more suitable for applications where space is limited and when foaming or scaling is a concern. However, in general, vertical tube evaporators are the preferred choice.

The boiling temperature of a solvent affects solubility positively. When the temperature of a solvent increases, the solubility of most solid solutes in that solvent also increases. This is because higher temperatures provide more energy for the solute particles to break apart and mix with the solvent particles, resulting in increased solubility. Therefore, the statement "Boiling temperature affects solubility positively" is correct.

A 1:1 heat exchanger is not a floating head heat exchanger. A 1:1 heat exchanger refers to a heat exchanger in which both the hot and cold fluids flow in a parallel arrangement, with each fluid having its own set of tubes. On the other hand, a floating head heat exchanger is a type of heat exchanger where one end of the shell is fixed while the other end is free to move, allowing for thermal expansion and contraction. Therefore, the statement that a 1:1 heat exchanger is a floating head heat exchanger is false.

In thin-walled tubes, when the ratio of the inner radius (rl) to the outer radius (r2) is greater than 1.5, the requirement for rm (mean radius) is not necessary. Therefore, the statement "In thin walled tubes when rl/r2 > 1.5, the rm is required" is false.

The given correct answer is "True". This means that for in walls, the outer temperature is equal to (tnt1). This implies that the temperature on the outer side of the walls is the same as the value represented by (tnt1).

The pressure inside the evaporator is lower than inside the condenser because the evaporator is responsible for absorbing heat from the surroundings, which causes the refrigerant to evaporate and thus decrease the pressure. On the other hand, the condenser is responsible for releasing heat to the surroundings, causing the refrigerant to condense and increase the pressure. Therefore, it is true that the pressure inside the evaporator is lower than inside the condenser.

An increased heating surface to liquid ratio is employed in film evaporators to enhance the efficiency of the evaporation process. This means that the heating surface area is larger compared to the volume of liquid being evaporated. By increasing the surface area available for heat transfer, more liquid can be evaporated in a shorter period of time. This allows for faster and more efficient evaporation, making the statement true.

A 1:1 heat exchanger does not have one baffle in each of the two tube heads. This statement is false because a 1:1 heat exchanger has one baffle in one tube head and no baffle in the other tube head.

The given equation Q= U.A.∆T/X is not true. The equation is missing an important factor, which is the thermal conductivity (k) of the material. The correct equation for heat transfer is Q= U.A.∆T/(X/k), where X is the thickness of the material. Therefore, the answer is false.

Evaporating pans are designed to handle continuous operation, meaning they can continuously evaporate liquid without the need for frequent interruptions or downtime. This makes them suitable for industrial processes that require a continuous supply of evaporated material. The design and construction of evaporating pans ensure efficient heat transfer and evaporation, allowing them to operate for extended periods without any issues. Therefore, the statement "Evaporating pans are suitable for continuous operation" is true.

Forced circulation evaporators are designed to handle high-viscosity liquids or liquids with a high fouling tendency. These evaporators use a pump to circulate the liquid through the heat exchanger at a high velocity, which helps in preventing fouling and scaling. By operating under reduced pressure, the boiling point of the liquid is lowered, allowing for more efficient evaporation. This also reduces the risk of thermal degradation of the liquid. Therefore, forced circulation evaporators can indeed be operated under reduced pressure.

Evaporation refers to the process of liquid turning into vapor. The statement correctly explains that evaporation occurs at a low temperature and for a short duration. This aligns with the scientific understanding of evaporation, where the liquid molecules gain enough energy to escape into the gas phase, but without reaching the boiling point. Therefore, the statement is true.

Steam traveling at a speed of a mile per minute is a factual statement. This means that steam can cover a distance of one mile in one minute.

The statement is false because in natural circulation evaporators, only a portion of the liquid is heated at a time. Natural circulation evaporators rely on the density difference between the heated liquid and the cooler liquid to create a natural circulation loop. As the heated liquid rises, it creates a flow that allows the cooler liquid to be heated. Therefore, not all the liquid is heated simultaneously in natural circulation evaporators.

Mechanical stem traps rely on buoyancy to operate. These traps work by using a float mechanism that rises and falls with the condensate level. When the condensate level is high, the float rises and opens the trap, allowing the condensate to drain. On the other hand, thermostatic traps operate based on temperature. They have a bimetallic element that expands and contracts with temperature changes. When the condensate is hot, the element expands and opens the trap, and when it cools down, the element contracts and closes the trap. Therefore, the statement that mechanical stem traps depend on buoyancy while thermostatic ones depend on temperature is true.

The statement is true because solute concentration does indeed increase viscosity and boiling temperature of a solution. When solute particles are added to a solvent, they disrupt the flow of the solvent molecules, making it more difficult for them to move past each other, resulting in an increase in viscosity. Additionally, the presence of solute particles in a solution raises the boiling point of the solution, as the solute particles create an additional obstacle for the solvent molecules to overcome in order to vaporize. Therefore, both viscosity and boiling temperature are directly influenced by the increase in solute concentration.

The statement suggests that the caldaria evaporator is indeed a vertical tube evaporator. This means that the caldaria evaporator follows the design and functions of a vertical tube evaporator, which typically consists of a vertical tube bundle where the liquid to be evaporated is heated and vaporized. Therefore, the answer "True" indicates that the given statement is correct and the caldaria evaporator can be classified as a vertical tube evaporator.

Simple thermostatic steam traps are not able to tolerate slight pressure variations. These traps are designed to operate within a specific pressure range, and any variations outside of this range can cause them to malfunction or fail. Therefore, the statement that slight pressure variations can be tolerated by simple thermostatic steam traps is false.

The statement contradicts itself by stating that heavy liquids are introduced from above and light liquids are collected from below. This suggests that both heavy and light liquids are present in the column, which means the liquids are mixed. Therefore, the correct answer is "Mixed".

The pressure regulator is a device that controls the pressure of a fluid, in this case, the refrigerant, in a system. By reducing the volume of refrigerant flowing to the evaporator, the pressure regulator helps to maintain the desired pressure levels in the system. This is important because the evaporator needs a controlled amount of refrigerant to efficiently absorb heat from the surroundings and cool the space. Therefore, the statement "The pressure regulator serves to reduce the volume of refrigerant flowing to the evaporator" is true.

This statement is true because moisture content in the air affects the rate at which water can evaporate. When there is higher moisture content, the air is already saturated with water vapor, making it more difficult for additional water to evaporate. Therefore, a lower evaporating temperature is required to facilitate the evaporation process.

Submerged solution in long vertical tube evaporators does not suffer from higher boiling temperatures. In fact, these evaporators are designed to operate at lower boiling temperatures compared to other types of evaporators. The submerged solution in the long vertical tubes allows for efficient heat transfer and evaporation, resulting in lower boiling temperatures. This design helps to prevent thermal degradation of the solution and ensures optimal evaporation efficiency. Therefore, the statement is false.

The statement is explaining the different ways in which radiation interacts with a material. It states that radiation can be reflected, transmitted, or absorbed. The portion of radiation that is transmitted through the material is then converted into heat. This suggests that there is a combination of both true and false aspects in the statement, hence the answer "Mixed".

The given statement suggests that an evaporating pan is composed of both a copper liner and a stainless steel jacket. This means that the pan is made using a combination of these two materials.

An evaporating still is a device used to separate a solvent from a solution through the process of evaporation. It is designed to work at low temperatures to prevent the degradation of heat-sensitive or thermo labile substances. Therefore, it allows the evaporation of thermo labile non-aqueous solutions without causing any damage or degradation to the solute. This statement is true because an evaporating still is specifically designed for this purpose.

The statement is true because boiling temperature can cause the degradation or decomposition of thermo labile substances during evaporation. Thermo labile substances are sensitive to heat, and when they are exposed to high temperatures during boiling, their chemical structure can be altered, leading to a loss of stability. Therefore, it is important to carefully control the boiling temperature to ensure the preservation of these substances during evaporation processes.

The statement is suggesting that melabile drugs should be evaporated at low temperatures for a short duration. This is likely true because melabile drugs are typically sensitive to heat and can easily degrade or lose their effectiveness when exposed to high temperatures for extended periods. Therefore, evaporating them at low temperatures for a short time would help preserve their chemical integrity and therapeutic properties.

The statement that "Latent heat is expressed in calorie/g/c" is false. Latent heat is actually expressed in calories per gram (cal/g) or joules per gram (J/g). The "c" at the end of the statement is incorrect and does not represent any unit of measurement.

The statement that "Vertical tube evaporator is a forced circulation evaporator" is false. A vertical tube evaporator is not a forced circulation evaporator. In a forced circulation evaporator, a pump is used to circulate the liquid through the evaporator tubes, while in a vertical tube evaporator, the liquid naturally rises due to the difference in density between the liquid and the vapor. Therefore, the correct answer is false.

The given statement is false. The first-deposited cake layers should not be formed under high pressure difference. In cake filtration, the pressure difference is gradually increased as the cake layer builds up. This allows for proper cake formation and effective filtration. Starting with a high pressure difference can result in uneven cake formation and reduced filtration efficiency.

Plate heat exchangers can indeed be used for multiple day time. Plate heat exchangers are devices that transfer heat between two fluids without mixing them. They consist of multiple plates with a large surface area, which allows for efficient heat transfer. These heat exchangers are commonly used in various industries, including HVAC systems, refrigeration, and chemical processing. They are versatile and can handle a wide range of temperatures and pressures, making them suitable for continuous operation over extended periods of time. Thus, the statement "Plate heat exchangers can be used for multiple day time" is true.

The statement is true because when the velocity of flow increases, it enhances heat transfer by improving the convective heat transfer coefficient. This is due to the fact that higher flow velocities create more turbulence and increase the contact between the fluid and the surface, leading to a more efficient transfer of heat. Therefore, increasing the velocity of flow can significantly enhance the heat transfer process.

Super-heated steam is not the preferred source of heat in industry. While steam is commonly used as a source of heat in industrial processes, super-heated steam is not as widely used. Super-heated steam is steam that has been heated to a temperature higher than its boiling point, and it can be more difficult to control and utilize compared to regular steam. Therefore, it is not the preferred choice for heat in most industrial applications.

Wet steam is not favorable for transportation across a factory because it contains a significant amount of water droplets. These water droplets can cause damage to equipment, reduce efficiency, and potentially lead to safety hazards. Dry steam, on the other hand, is preferred for transportation as it contains minimal moisture content and is more suitable for various industrial processes. Therefore, the statement that wet steam can favorably be transported across the factory is false.

The statement that boiling temperature is inversely proportional to external pressure is false. In reality, boiling temperature is directly proportional to external pressure. As pressure increases, the boiling temperature also increases. This can be observed when cooking at high altitudes, where the lower atmospheric pressure causes water to boil at a lower temperature. Conversely, in a pressure cooker, the higher pressure raises the boiling temperature, allowing food to cook faster.

Falling film evaporators are not preferred to wiped film evaporators for very viscous liquids. Wiped film evaporators are more suitable for processing highly viscous liquids because they have a mechanism that helps in continuously removing the liquid from the evaporator surface, preventing any buildup or fouling. This allows for efficient heat transfer and evaporation. Falling film evaporators, on the other hand, are better suited for low viscosity liquids as they rely on gravity to create a thin film of liquid that flows down the evaporator surface.

A thermostatic steam trap is designed to automatically discharge condensate from steam systems. It operates based on the temperature difference between steam and condensate. When steam enters the trap, the thermostatic element expands and opens the trap, allowing condensate to be discharged. This mechanism also allows the trap to act as a vent, as it can release air and other non-condensable gases from the system. Therefore, a thermostatic steam trap can indeed be used both as a vent and a drip.

The statement suggests that spiral heat exchangers are similar in size and cost to tubular units, or even cheaper. This means that spiral heat exchangers can provide a cost-effective alternative to tubular units while still achieving similar performance.

Insulin extract can be safely evaporated in a climbing film evaporator because this type of evaporator allows for efficient and controlled evaporation of liquids. The climbing film evaporator operates by creating a thin film of liquid on the inner surface of the evaporator tubes, which enhances heat transfer and minimizes the risk of overheating or degradation of the insulin extract. This method ensures that the evaporation process is safe and preserves the quality and effectiveness of the insulin extract.

Plate heat exchangers actually offer higher heat transfer for viscous liquids compared to finned tubes. This is because plate heat exchangers have a larger surface area for heat transfer, allowing for more efficient heat exchange between the two fluids. The plates in a plate heat exchanger are corrugated, which creates turbulence and enhances heat transfer. On the other hand, finned tubes are more commonly used for air-to-fluid heat transfer applications. Therefore, the statement that finned tubes offer higher heat transfer for viscous liquids than plate heat exchangers is false.

The statement suggests that thick lagging with only small areas exposed is more efficient than thin lagging everywhere. This implies that the insulation provided by thick lagging is better than thin lagging. Therefore, the correct answer is False, as it contradicts the statement.