EXPERIMENTAL ANALYSIS TO ENHANCE THE PERFORMANCE OF SHELL AND TUBE EXCHANGER WITH RIBS

: Heat transfer has always been a significantly interesting topic with an eye towards developing highly efficient, inexpensive & light weight Heat Exchangers. This project is about enhancement of heat transfer through ribs. Ribs are an efficient & economic tool in heat transfer enhancement which can be used as an obstruction to fluid flow in order to promote turbulence, which would result in comparative increase in the amount of fluid particles coming in contact to the surface and also enhances the overall heat transfer coefficient by disturbing the fluid flow that would break thermal & viscous boundary layers. As a consequence of this, there will be a significant improvement in the Effectiveness of a Heat exchanger. In this study, a Shell & tube heat exchanger is designed, fabricated and also analyzed, where numerous tests are carried out with varying the number of Ribs utilized in the heat exchanger, in order to obtain a substantial increase in: i) Effectiveness ii) Overall Heat transfer coefficient.


INTRODUCTION 1.1 Heat Exchangers
Without blending or mixing the fluids, heat is transferred between them via heat exchangers.A partition that has a high heat conductivity separates the fluids.The partitions thickness is intended to fend off the fluids from combine or coming into touch directly with one another.Heat is transferred between fluids via heat exchangers, which do not blend or mixed the fluids.A partition with a toll heat transfer keeps the fluids apart.The partition thickness is intended to avoid the possibility of direct contact between the fluids or their mixing.An active that rejects or ingests heat from the treated liquid is a part of the process.The process results in either heating or cooling of the fluid stream.Heat exchangers come in countless varieties, with new ones being created every year as technology advances and our understanding of the characteristics of different metals grows Boilers and other fuel-, electrical-, or nuclear-powered heat transfer devices are not heat exchange devices.Both the heat energy source and the heat recipient must be flowing substances.Liquids, gases, and vapors are all considered to be fluids as they all flow when shear stress or an external force is applied.

Plate and Frame Heat Exchangers:
To prevent the two fluids from mixing, there are several corrugated plates.Are connected by a braze, weld, or gasket.The plates contain ports on the corners that let fluid streams enter and exit.The fluid streams are set up in a hot-cold-hot-cold flow pattern.Patterns in the gaps

LITERATURE REVIEW
The information below lists previous literature reviews on the subjects of improving heat transfer, shell and tube heat exchangers, and ribs that have been published in research papers, journals, and articles.
[1], studied shell and tube type heat exchangers and their applications is covered in this work, along with references to other researchers who have made contributions in this area.Additionally, the study goes into great length into the specifics of construction, design approaches, and the factors that led to the widespread acceptance of shell and tube type heat exchangers.
[2], Based on the full Bell-Delaware approach, they have presented a concise formulation to connect the shell-side pressure drop with the exchanger area and the film coefficient.They have also created a compact pressure drop equation for the tube-side stream, which takes into consideration both straight pressure drops and return losses, in addition to the derivation of the shell side compact expression.They have demonstrated how an effective design algorithm can make use of the concise formulations.They discovered that the suggested algorithms performed satisfactorily across the whole range of geometries for single phase, shell and tube heat exchangers.[3], had found that different problem formulations required different techniques to be used.These problem formulations related to (i) heat transfer area or total annualized costs, (ii) constraints, such as pressure drop and velocity bounds, and (iii) decision variable, such as the choice of various search variables and their classification as integer or continuous.In this essay, the design of shell and tube heat exchangers is optimized.
The formulation of the issue is to minimize the thermal surfaces of the apparatus while taking into account discrete decision factors, minimum surplus area, and maximum pressure drops.In order to approach the solution to the design practice, significant extra constraints that were typically overlooked in earlier optimization schemes are introduced.
[4], In order to investigate the effects of rib shape on heat transfer, the thermal performance characteristics of pipe flow with three different types of rib tubes-elliptic, circular, and square-were tested for Rein ranges of (5,000-15, 000).Additionally, the renormalization group k-model was used in ANSYS -FLUENT 6.3 to simulate turbulence.
The results of the comparison between the temperature and velocity distributions along the tube for a tube with internal ribs and a smooth tube indicate that the use of internal ribs increases the rate of heat transfer and has the highest performance factors for turbulent flow.[5], improved heat transmission in a heat exchanger by using a helical strip in a circular pipe using regular water as the working fluid.The use of heat exchangers in industrial processes and engineering applications is fairly common.Due to the swirling motion of the fluid stream and disturbance of the boundary layer caused by this shape, the effective surface area, residence time, pressure drop, and heat transfer coefficient are all increased.Heat transfer rates increase by up to 50% to 70% when twisted pipe is used instead of simple pipe.
However, because of the intense turbulence stream, the pressure loss in the other section also increases dramatically by up to 90%.In the case of a variable twist ratio, pressure drop and heat transfer coefficient both rise as the twist ratio does.

Objectives
Increasing the surface's heat transfer area can generally improve heat transmission from the surface.Most of the time, expanded surfaces are used to increase heat transfer, which can be costly because it requires more material and takes up more area.
The improvement of heat transfer is one of the important subjects utilized for creating very efficient, affordable, and light-weight heat exchangers.By disrupting the fluid flow and rupturing the viscous and thermal boundary layers, repeated ribs can be utilized to increase turbulence and the convective heat transfer coefficient.
The ribs' obstacles make it easier for the fluid to mix, which raises the Reynolds number and, in turn, the convective heat transfer coefficient.Both an increase in heat transfer area and a noticeably higher heat transfer coefficients are introduced by the presence of ribs on the heat exchanger walls and the airfoil cooling walls.
The creation of the flow field is significantly impacted by the rib's cross section.
The separation of the boundary layer, attachment, and hot spots that have been formed are all affected by the rib shape.The parameters of fluid flow and heat transmission from a rectangular rib-roughened duct with varied rib forms have been studied in the current work.
An equal-aspect-ratio rectangular channel with a rectangular shape is part of the experimental setup.

Ribs in a Shell & tube heat exchanger
The hot fluid (gas, water, glycol, refrigerant, etc.) moving through the coil's tubes is crucial for the coil's overall efficacy; coupled with airside heat transfer, it makes up half the battle.The performance of the coil and a system's overall effectiveness are influenced by how much the fluid contacts the tube walls.The fluid's ability to transport heat is improved and made more cost-effective the more contact it has with the tube wall.
The use of devices known as "ribs" is one method of creating this desired turbulent flow.When introduced into a tube containing hot fluid, ribs change the flow of the fluid by increasing contact with the tube wall, which causes more hot fluid to lose heat to the cold fluid surrounding the tubes.Additionally, the boundary layer that is concentrated close to the   Metal Plate: To prevent the mixing of hot and cold fluid in the front head, a metal plate is employed as a partition or separator between the inlet and exit ports.To stop any leaks, this metal plate is positioned inside the Front head and arc-welded to it.ii.
Holes: 8 holes with equal spacing and 8mm holes are drilled into the side flange of the front head.Pipe Joint: To fix input & outlet ports, a few 100mm long pipe joints need to be installed on the face of the front head.To fix these ports, holes must first be drilled at the necessary locations, and the surface is then polished with sandpaper.Following the welding of the pipe joints to the front head, the nozzles are attached to the pipe joints.iv.
Nozzles: A nozzle is a tool used to change the characteristics of a fluid flow as it leaves (or enters) a closed chamber or conduit, particularly to enhance velocity.A nozzle is typically a pipe or tube with a variable cross sectional area that is used to control, direct, or alter the flow of a fluid.

Tube assembly
The design and fabrication of the Tube assembly consists of four components,    ii.
Following the plotting of the points on the baffle, which is then secured in a vice, holes are drilled through the points using a drilling machine.The copper tubes' outer diameter is the same as the diameter of the hole. iii.
These drilled baffle plates have now had their diameter reduced by 20-25% to allow for the flow of cold fluid in the shell.

iv.
After the points are plotted on the baffle it is fixed to a vice, holes are drilled in them with drilling machine.And the diameter of the hole is the outer diameter of the copper tubes.

v.
These drilled baffle plates are now reduced in diameter by 20-25% to permit the flow of cold fluid in the shell.

vi.
After carefully inserting copper tubes into each hole created in the baffles after drilling the holes, the baffles are complete.The adjacent baffle plates are evenly placed so that there is sufficient turbulence produced by the cold fluid to remove sufficient fluid.

vii.
After carefully spacing the baffles, it's crucial to mark their locations on the copper tube since doing so will make it easier to equally position the baffles when the tube assembly is taken apart for maintenance or repair.Pumping cold water (Ci) from the sump into the common inlet point causes the flow to be routed at a T-Joint to the shell intake valve and the heater inlet valve. ii.
Following the water's exit from the shell and tube, the valves are adjusted to provide the necessary flow rate.The flow rate is then monitored, held constant, and reported (mh& mc). iii.
Water is immediately heated as it enters the heater through the heater's inlet valve.
The heater's hot water is pumped into the shell's front head.Now, the temperature of the heated water as it enters the shell's front head is measured and recorded as hi. iv.
As hot water runs through the copper tubes and into the shell, it loses heat to the cold water.When the hot fluid reaches the back of the shell, it reverses course and moves backward through the upper tubes, where it once more loses heat to the chilly water circulating inside the shell.
v. Finally, the cold fluid leaves the shell through the output port and the heated fluid escapes through the rear head.A sensor at the available sensor heads measures the exit temperatures of the two fluids, ho and Co.

vi.
A second time, the procedure is run with a variable flow rate, and then by

Experimental procedure
The objective of this experiment is to provide experimental proof of Heat transfer enhancement through ribs by determining the following quantities: i. Total heat transfer rate(Q) ii.

Overall heat transfer coefficient(U)
iii.
Effectiveness of the heat exchanger(ε) To demonstrate experimentally how ribs can improve heat transfer, the following analysis and calculations are carried out i.
For 32 tubes with three different sets mass flow rates. ii.
For 24 tubes with varying Ribs percentage: a) First set of fixed mass flow rates of hot & cold fluid with 0%, 25%, 50%, 75%, 100% ribs inserted in copper tubes b) Second set of fixed mass flow rates of hot & cold fluid with 0%, 25%, 50%, 75%, 100% ribs inserted in copper tubes The use of ribs in a sell-and-tube heat exchanger would increase the rate of heat transfer as well as the effectiveness of the heat exchanger, and this would be demonstrated experimentally, mathematically, and graphically at the conclusion of our investigation.
So to get a better understanding of this, the following procedure is implemented: i.
The experiment is first run on 32 tubes to calculate the total heat transfer rate, overall heat transfer coefficient (U), and heat exchanger effectiveness.ii.
The same numbers are measured again, this time depending on the percentage of ribs put in these freshly constructed and engineered tubes, while maintaining the same area of heat transmission and reducing the number of tubes to 24.The readings from these 24 tubes are now noted in the manners described below; c) First set of fixed mass flow rates of hot & cold fluid with 0%, 25%, 50%, 75%, 100% ribs inserted in copper tubes.d) Second set of fixed mass flow rates of hot & cold fluid with 0%, 25%, 50%, 75%, 100% ribs inserted in copper tubes.

Numerical Calculations
As mentioned above, the calculations are executed as follows: iii.
For 32 tubes with three different sets mass flow rates. iv.

Experimental observations
Following values of the experiment conducted with 32 tubes

CONCLUSIONS
The shell and tube heat exchanger with 24 and 32 tubes through a number of tests the following results are displayed as graphs and are also obtained by altering the Ribs% inserted in the 24 copper tubes.

Comparison between 32 tubes vs 24 tubes
As can be seen in the graph above (graph 21), the Shell & tube heat exchanger's efficiency increased significantly as the number of copper tubes was reduced, maintaining the area of heat transfer constant and conceptually increasing the tube diameter As can be seen in the graph above (graph 21), the Shell & tube heat exchanger's efficiency increased significantly as the number of copper tubes was reduced, maintaining the area of heat transfer constant and conceptually increasing the tube diameter.

Flow rate vs Ribs in 24 tubes
The shell and tube heat exchanger was put through a number of tests utilizing two sets of flow rates and altering the number of ribs inserted in the copper tubes by 0%, 25%, 50%, 75%, and 100%.Finally, graphics are used to depict the analysis and calculations of the given data for ease of comprehension.
/doi.org/10.1051/e3sconf/202343001235235 430 between the plates.Cold fluid flows up and hot fluid flows down the plates in an arrangement known as a countercurrent flow.

Figure. 1 .
Figure.1.Plate and Frame Heat Exchangers However, the fluids have a considerable pressure loss because to the high wall shear stress, which drives up the cost of pumping.A considerable temperature different between the fluids is likewise not recommended for use.

[ 6 ]
, Investigated the effectiveness of internal cooling in most devices employing ribs.The rate of heat transmission is accelerated by ribs because they disturb the boundary layer and increase turbulent kinetic energy.The majority of research focuses on the square and rectangular rib forms.
/doi.org/10.1051/e3sconf/202343001235235 430 /doi.org/10.1051/e3sconf/202343001235235 430 heat transfer surface is broken up by the turbulence created by the ribs, increasing the heat transfer coefficient in the current system.

3. 3 . 3
Figure.7.Tube arrangement of 3D model diagram in different views Figure.8.Assembly of Tubes 3.4 Operational procedure and analysis i.Pumping cold water (Ci) from the sump into the common inlet point causes the flow /doi.org/10.1051/e3sconf/202343001235235 430

9 .
Figure.9.Shell and tube heat exchanger with rib diagramThe readings from these 24 tubes are now noted in the manners described below; a) First set of fixed mass flow rates of hot & cold fluid with 0%, 25%, 50%, 75%, 100% ribs inserted in copper tubes.

Parameters Front head Rear head Shell
3.2.1 Shell :The heat exchanger's main mass or body is called the shell, which is occasionally also referred to as the housing.It is constructed in the form of a cylinder.Cold fluid enters and exits the shell through two ports, called the inlet and exit ports

Mass flow rate vs Effectiveness (ε) Graph: 4 Mass flow rate vs U (w/m 2 K) GRAPHS:
Following are the results of the experiment conducted with 25 tubes: Graph :19 Ribs (%) vs Efficiency (%)Graph :20 U(w/m 2 K) vs LMTD,(∆T)LM Based on the comparison graphs of all the mentioned cases a table is constructed for a border insight: