Does heat transfer require temperature difference?
The rate (in W) at which heat transfers from the hotter object to the colder object increases with the temperature difference between the objects. Short Answer: The greater the temperature difference, the greater the rate at which heat transfers. Heat is transferred by one or more of three processes.
What are the factors that affect the heat transfer capacity of an evaporator?
The overall heat transfer coefficients were affected mainly by temperature difference between the liquid evaporating and the steam condensing temperatures, evaporating temperature, irrigation density, liquid viscosity, and the heating tube length, but the Prandtl number was also significant.
For what value of end temperature difference ratio is the arithmetic mean temperature difference 5% higher than the log mean temperature difference?
For what value of end temperature difference ratio, is the arithmetic mean temperature difference 5% higher than the log-mean temperature difference? Explanation: α 1/ α 2 = 2.2.
How do you calculate the heat transfer of an evaporator?
- Heat balance. Heat available per kg of steam. = latent heat + sensible heat in cooling to 91°C. = 2.164 x 106 + 4.186 x 103(134 – 91)
- Heat-transfer area. Temperature of condensing steam = 134°C. Temperature difference across the evaporator = (134 – 91) = 43°C.
- Heat balance.
How do you find the heat transfer area of a condenser?
4.0 – HEAT EXCHANGERS CALCULATIONS:
- The main basic Heat Exchanger equation is: Q = U x A x ΔTm =
- The log mean temperature difference ΔTm is: ΔTm =
- (T1 – t2) – (T2 – t1) = °F.
- T1 = Inlet tube side fluid temperature; t2 = Outlet shell side fluid temperature;
- ln (T1 – t2) (T2 – t1)
How do I know what size evaporator I need?
Multiply the answer by your proposed volumetric flow rate, measured in gallons per minute. If the evaporator must move 400 gallons per minute: 14 x 400 = 5,600. Multiply the answer by 500: 5,600 x 500 = 2,800,000. This answer is the evaporator’s size, measured in BTUs per hour.
What does TD mean in HVAC?
evaporator’s temperature difference
How do you calculate TD condenser?
Actual condenser T.D.can be calculated by dividing the design THR by the 1°F T.D.Condenser T.D.Rating. Actual condensing temperature can be calculated by adding the actual condenser T.D.to the design ambient temperature. Actual Condensing Temp. = Ambient Temperature + Actual T.D.
How do I choose an evaporator?
A properly designed evaporator must, at a minimum:
- Be designed to effectively transfer heat at a high rate with minimum surface area to be cost-effective for installation,operations and maintenance.
- Effectively separate the vapor from the liquid concentrate.
- Meet the conditions required by the product being processed.
How do you choose a condenser capacity?
Air-Cooled Condenser Sizing & Selection
- Selection Example: Compressor capacity: 45,000.
- Step 1: Estimate Condenser THR.
- Step 2: Correct for Altitude.
- Step 3: Calculate Design Condenser TD.
- Step 4: Condenser Selection.
- Step 5: Calculate Actual TD and Condensing Temperature.
How do I choose a condenser coil?
When selecting the necessary condenser coil, the entire rear of the shell should be uti- lized as condenser area. The tube spacing should be selected between 60-l00 mm to obtain a reasonable U-value.
How do you make a condenser?
Design of condenser
- • Introduction • A condenser is a type of heat exchanger in which vapors are transferred into liquid state by removing the latent heat with the help of a coolant such as water.
- Different types of the Condenser 1.
In which condenser heat is removed by air?
In air cooled condensers, heat is removed by air using either natural or forced circulation. The condensers are made of steel, copper or aluminum tubing provided with fins to improve air-side heat transfer. The refrigerant flows inside the tubes and the air outside.
What is the definition of condenser?
A condenser is a vessel or stage which turns a vapor into a liquid. A compressor is used to pump that vapor to a condenser, where the vapor turns back into a liquid, ready for reuse. Condensers are special heat exchangers that remove the heat of vaporization from steam.
What is difference between condenser and compressor?
The compressor “squeezes” the gas. It actually changes the gas refrigerant into a liquid, which is used throughout the A/C system to eventually produce cold air. The condenser is responsible for taking the pressurized gas from the compressor and changing it into a liquid vapor.
Which type of condenser is most commonly used for household purposes?
Shell-and-tube type: This is the most common type of condenser used in systems from 2 TR upto thousands of TR capacity. In these condensers the refrigerant flows through the shell while water flows through the tubes in single to four passes. The condensed refrigerant collects at the bottom of the shell.
Which is the simplest method of cooling the condenser water?
Spray cooling pond
Which type of condenser is best for AC?
Copper has a heat transfer coefficient higher than aluminium. That means, copper is a better heat exchanger than aluminium. 2) Cost and Pliability (The quality of being easily bent): Copper is costlier than aluminium, which increases the cost of making an air conditioner and thereby the price of air conditioner.
What is the difference between jet condenser and surface condenser?
1.2. 1 Types of Surface Condensers: 1.2. 1.1 Down flow condenser….Difference between surface condenser and jet condenser.
| S.NO | Surface Condenser | Jet or Direct Contact Condenser |
|---|---|---|
| 3 | Condensate is reused. | Condensate is wasted |
| 4 | It requires large quantity of circulating water. | It requires less quantity of circulating water |
What are the merits and demerits of surface condenser?
ADVANTAGES AND DISADVANTAGES OF A SURFACE CONDENSER
- The condensate can be used as boiler feed water.
- Cooling water of even poor quality can be used because the cooling water does not come in direct contact with steam.
- High vacuum (about 73.5 cm of Hg) can be obtained in the surface condenser.
- The capital cost is more.
How vacuum is created in surface condenser?
Vacuum Importance in Condensing System In other words, the specific volume of water at a given pressure is many times lower than that of steam. This enormous reduction in volume creates the vacuum inside the condenser. This partial vacuum will draw in more gas to be cooled.
Why it is called surface condenser?
In thermal power plants, there are usually surface condensers as the main condenser. The exhausted steam from the LP turbines is condensed by passing over tubes containing water from the cooling system. Thermal power plants are usually equipped with so called “surface condensers”.
Why vacuum is maintained in condenser?
The removal of air and other noncondensable gases from the condenser shell side is required for proper heat transfer from steam to cooling water in the condenser and, thus, to maintain high vacuum in the condenser.
What is use of the air pump in the condenser?
For reducing the amount of steam mixed with the air sucked by the air pump, the steam condenser has a portion of tubes near the air pump suction screened off and the condenser tubes in this portion contain the coldest water, and the number of cooling tubes is increased.
Which of the following is a type of surface condenser?
Surface Condenser Types
| Jet Condenser | Surface Condenser |
|---|---|
| Both steam & cooling water are mixed together | Both steam & cooling water are not mixed together |
| Manufacturing cost is low | Manufacturing cost is high |
| Occupies less area | Occupies large area |
| The air pump requires large power | The air pump requires less power |
Which of the following is not a type of condenser?
1. Which of the following is NOT a type of surface condenser? Explanation: Ejector condenser is a type of jet condenser and not a surface condenser.
Why condenser is used in Rankine Cycle?
In a Rankine cycle, the liquid water is superheated in the boiler. From the turbine exit the steam is sent to the condenser for condensation and after condensation, the liquid water is sent to the boiler again.In the condenser, the steam rejects heat to the surrounding.
What are the sources of air leakage in condenser?
The condenser has high vacuum, therefore air leakage occurs in the condenser. The main sources of air leakage in the condenser are: (i) Leakage of air from atmosphere at the joints of the parts which are at pressure less than atmospheric pressure. (ii) Air is coming from the boiler along with steam.