How do you evaluate a heat exchanger performance?
The simplest indicator of the performance of a heat exchanger is the temperature change of the fluid under consideration. From our high school lessons on thermodynamics, we can recall that the rate of heat transfer is the product of the rate of heat capacity and the temperature change.
What are the selection criteria of heat exchanger?
Main Criteria for Heat Exchanger Sizing and Selection For a gasketed plate heat exchanger, the gaskets must be compatible with the fluids in the unit. Thermal fluid characteristics and product mix. If the heating or cooling fluid is susceptible to fouling, a corrosion resistant material may be needed. Location.
How does a coaxial heat exchanger work?
The coaxial heat exchanger in the heat pump exchanges heat between the ground loop and the refrigerant. o When the heat pump is set to work in heating mode, this exchanger works as an evaporator. The refrigerant evaporates as it takes the energy from the ground.
Which heat exchanger design is the most efficient?
Plate exchanger is the most efficient due to turbulent flow on both sides. High heat-transfer coefficient and high turbulence due to even flow distribution are important. However, a plate heat exchanger regenerator is restricted to low viscosities. With high viscosities, a special tubular may be required.
What is a good heat exchanger effectiveness?
Average efficiency may be around 85% to 90%. you can calculate the performance of the heat exchanger with respect to heat transfer rate to the maximum heat transfer which is calculated theoratically.
Which is correct for calculation of effectiveness of heat exchanger?
If one of the fluids is undergoing a change of phase throughout the entire heat exchanger and at a constant temperature (i.e. heat capacity is infinite), the thermal efficiency is simply Eff=1-exp(-U.A/Cmin), where Cmin is the heat capacity (m x cp) for the single phase fluid, U-overall heat transfer coeffcient and A …
What are the factors are involved in designing a heat exchangers?
Designing heat exchanger The main factors affecting the performance heat exchanger tubes include: fluid velocity, tube diameter, converter tube shape (U or cross shape), converter layout order (horizontal or vertical), and Venting valve, material of tube sheet and channel and location order of input channel.
How do you design a heat exchanger?
How to Design a Tubular Heat Exchanger?
- How to Design a Tubular Heat Exchanger.
- Step 1: Analysing the Application.
- Step 2: Identifying the Fluid Properties.
- Step 3: The Energy Balance.
- Step 4: Defining the Geometry of the Heat Exchangers.
- Step 5: Thermal Calculation.
- Step 6: Interpretation of the Thermal Calculation.
What are coaxial heat exchangers made of?
The coaxial heat exchanger is designed as a “tube in tube” structure. The outer tube is made of steel/copper, and the inner tube can be titanium, copper, copper-nickel depending on the requirements of working condition.
How does a heat exchanger work?
How Do Heat Exchangers Work? Heat exchangers, metal shells and tubes, work by transferring heat from one place to another. When a furnace burns natural gas or propane fuel, its exhaust/combustion by-products (also known as flue gas) enter and travel through the heat exchanger.
How can the efficiency of a heat exchanger be improved?
One simple and obvious solution for increasing shell-and-tube heat exchanger performance might be to switch the shell-and-tube fluids. The placement of the process fluids on the tube or shell side is usually not dependent on the most efficient heat transfer area. A primary concern is pressure.
On which parameters the effectiveness of heat exchanger depends and how?
Effectiveness of the heat exchanger depends on the thermal conductivity and convective heat transfer coefficient of the fluid. The convective heat transfer coefficient of nanofluids depends on the thermal conductivity, density, specific heat, and viscosity of the nanofluids .
How do you calculate heat exchanger capacity?
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. Where:
- T1 = Inlet tube side fluid temperature; t2 = Outlet shell side fluid temperature;
- ln (T1 – t2) (T2 – t1)
What are the factors are involved in designing a heat exchanger?
What is mechanical design of heat exchanger?
Mechanical design includes checking the physical stability of heat exchanger to have a safe design without any failure. Components like tubesheets, shell, channel cover, etc.
What is a coaxial condenser?
Design and operation: Coaxial tube-in-tube water-cooled condensers use two nested tubes to achieve a counter-flow design, where water flows in the opposite, or “counter,” direction to the refrigerant. During operation, fluid passes through the inside tube while simultaneously cooling the refrigerant in the outer tube.
What is a coaxial coil?
Doucette Coaxial Coils are designed for use as Water Cooled Condensers, Water Chillers and in Water Source Heat Pumps. This design is being used by major OEM’s around the world and in the ever expanding wholesale replacement market. Simplicity of design and installation makes this product ideal in both markets.
Why coaxial borehole heat exchanger?
The coaxial borehole heat exchanger (BHE) has been selected because for the present conditions it has a better performance than the conventional U-tube BHE. A numerical model has been developed to study the coaxial BHE. The model predictions are compared to detailed distributed temperature measurements obtained during a thermal response test.
Do boreholes affect the flow direction of the heat carrier?
While for boreholes in the range of (≈200 m) it is seen that there is little or none obvious effects related to the flow direction of the heat carrier, larger effects are seen for deeper boreholes.
Why coaxial BHE with inlet through the annular space?
With increasing depth, the coaxial BHE with inlet through the annular space is superior for heat extraction for two distinct reasons. Firstly, it mimics the behavior of a counter-current heat exchanger (which has the highest theoretical thermal efficiency), and secondly, it can easily be improved through improving the insulation of the center pipe.
How to improve the thermal efficiency of a heat exchanger?
Firstly, it mimics the behavior of a counter-current heat exchanger (which has the highest theoretical thermal efficiency), and secondly, it can easily be improved through improving the insulation of the center pipe. 5.3. Flow direction (case of a 490 m deep BHE)