Design and CFD Simulation of Heat Transfer in Circular Pipes

Abstract

A major issue for human growth is the energy crisis. In the current study, circular pipes are considered an energy-efficient technology viable in all seasons. It uses non-constant soil temperature and water flow in coldest regions. This model reports the thermal performance of pipes with different results in hot and cold climates. To degree thermal performance, pipe version changed into advanced and simulated with ANSYS 18.1 Fluid Flow (Fluent). Data was collected from two modelled summer and winter seasons. Continuity, momentum, and energy equation have been used for the simulation. Comparison analysis is also being carried out about the obtained results with previously published articles. The effects of summer and winter temperature and speed on performance were also evaluated. Further, the graphical interpretation is also carried for velocity and pressure distribution. The study highlights a drastic drop in temperature and velocity near the inlet and outlet region while Pressure is inversely proportional to velocity in these regions. It is also obtained from the simulation that the temperature pressure and velocity remain uniform in the fully develop region.

1 Introduction

The use of energy is an integral part of the progress of human society, playing a role in controlling and adapting to the environment. There is a gradual increase in the consumption of various types of energy around the world. Several researchers studied about the Potential for supply temperature reduction of existing district heating substations [1,2,3]. This rise in energy demand is mostly caused by population and income growth [4]. The heat transfers and pressure drop of the perpendicular GHE is dissembled with different inflow rates, pipe compasses, and well depths. Li et al. [5] investigated the thermic response tests evaluation of borehole heat exchanger thermal short and effective. The liquid absorbs or rejects heat with the surface through the downhole leg (DLP) and top of the tube (ULP) inside a perpendicular drag heat exchanger (BHE). Since the periphery of the hole is only 0.11−0.2 m, the temperature difference between DLP and ULP will inescapably beget a thermal short circuit probing the effect of different geometric features on the short circuit. The heat transfer between the two legs was developed into a 2-D model, after which the most suitable expression for the thermal resistance of the short circuit was presented without dimension. Sotgia et al. [6] experimental analyzed the inflow contours and pressure drop reduction of oil painting-water fusions. They performed an experimental study of nonstop oil painting-water inflow in vertical pipes with mineral oil painting and valve water with a density rate of roughly 900 and a viscosity rate of 0.9. Seven different pyrex and plexiglass tubes with a periphery of 21-0 mm were used. Kim et al. [7] suggested that numerical analysis of the evolution of laminar flows extending from a spiral pipe to a straight pipe. Li et al. [2, 3, 4. Mesh generated with Design Modeler in ANSYS 18.1. The mesh creates a large number of cells in the far-field Cartesian layout and provides accurate fluid flow results. An optimal number of 3093 nodes and 11,548 elements were generated in the mesh to obtain perfect results for this case.

Fig. 2

Mesh at the pipe’s inlet

Fig. 3

Mesh at the pipe’s

Fig. 4

Mesh at the pipe’s outlet

2.2 Mathematical Equations

The mathematical equation of continuity Navier Stoke’s equation and energy equation are given as:

$$\frac{\partial {\rho }_{1}}{\partial t}+\frac{1}{{r}_{1}}\frac{\partial }{\partial {r}_{1}}\left({\rho }_{1}{r}_{1}{u}_{{r}_{1}}\right)+\frac{1}{{r}_{1}}\frac{\partial }{\partial {\varphi }_{1}}\left({\rho }_{1}{u}_{{\varphi }_{1}}\right)+\frac{\partial }{\partial z}\left({\rho }_{1}{u}_{{z}_{1}}\right)=0$$

(1)

Navier–Stoke equation is used. Cylindrical coordinates.

$$\begin{aligned} \frac{{\partial u_{{z_{1} }} }}{{\partial t}} + u_{r} \frac{{\partial u_{{z_{1} }} }}{{\partial r_{2} }} + \frac{{u_{{\varphi _{3} }} }}{r}\frac{{\partial u_{{z_{1} }} }}{{\partial \varphi _{3} }} + u_{{z_{1} }} \frac{{\partial u_{{z_{1} }} }}{{\partial z_{1} }} = & - \frac{1}{\rho }\frac{{\partial p}}{{\partial z_{1} }} + g_{1} \\ & + v\left[ {\frac{1}{{r_{2} }}\frac{\partial }{{\partial r_{2} }}\left( {r_{2} \frac{{\partial u_{{z_{1} }} }}{{\partial r_{2} }}} \right) + \frac{1}{{r_{2} ^{2} }}\frac{{\partial ^{2} u_{{z_{{1{\text{~}}}} }} }}{{\partial \varphi _{3} ^{2} }} + \frac{{\partial ^{2} u_{{z_{1} }} }}{{\partial z_{1} ^{2} }}} \right] \\ \end{aligned}$$

(2)

The temperature difference in the (low speed) flow is small enough for K to be assumed constant.

$$\frac{\partial T}{\partial t}+u\frac{\partial T}{\partial x}+v\frac{\partial T}{\partial x}=k\left(\frac{{\partial }^{2}T}{\partial {x}^{2}}+\frac{{\partial }^{2}T}{\partial {y}^{2}}\right)$$

(3)

where $k = k/{\rho c\rho}$ is the thermometric conductivity. It is Use the energy equation to change boundary conditions temperature such as water as well as surrounding temperature. We obtained these results from Ansys 18.1.

3 Results and Discussion

Inlet temperature profiles with constant velocity $v = 0.425\,{\text{m/s}}$, the constant inlet temperature of the water is 278 k, and different walls of the temperature such as 272 k.

The effect of low liquid cargo on colorful inflow characteristics and problems related to inflow resistance, like pipe erosion, suggest that further analysis of inflow is demanded. In this study, CFD simulations were performed on a vertical pipe where liquid and gas are fed independently at constant haste at the bay. The analysis substantially focuses on the shape of the interface, the haste fields in the liquid and gas phases, the liquid retention, and the shear stress profile. Tests are performed as a liquid phase with water or oil painting, the liquid volume bit in the bay sluice is 0.0005 to 0.00020. Overall, the results help to understand the miracle of low liquid charge inflow. It can be seen from Figs. 5 and 6 the inlet of the pipe temperature/velocity contours are given below. Inlet temperature profiles as seen in Fig. 7, with constant velocity $v = 0.425\,{\text{m/s}}$ the constant inlet temperature of the water is 278 k, and different walls of the temperature such as 272 k, 267 k, and 262 k.

Fig. 5

Inlet temperature contours with v = 0.425 ${\text{m}}/{\text{s}}$

Fig. 6

Inlet velocity contours, v = 0.425 ${\text{m}}/{\text{s}}$

Fig. 7

Inlet temperature profiles with v = 0.425 m/s Inlet T w (K) = 278 k, Wall of the T p (K) = 272 k

Simulations are performed with Ansys Fluent 18.1 using Volume of Fluid. Inlet velocity profiles as seen in Fig. 8, with constant velocity $v = 0.425\,{\text{m/s}}$, a constant inlet temperature of the water is 278 k, and different walls of the temperature such as 272 k, 267 k, and 262 k.

Fig. 8

Inlet velocity profiles with v = 0.425 m/s Inlet Tw (K) = 278 k, Wall of the Tp (K) = 272 k

Figure 7 indicates that the temperature of the water increases gradually and maximum in the grown region of the pipe. The wall temperature of the pipe is 272 k or (−1 $^\circ{\rm C}$). When water flows in the pipelines initially temperature gradually increases. When the fluid reaches a fully developed region then the temperature is maximum.

Figure 8 displays that the velocity of the water increases gradually and maximum in the fully grown region of the pipe. Wall temperature of the pipe is 272 k or (−1 $^\circ{\rm C}$). When water flows in the pipelines initially velocity gradually increases. When the fluid reaches a fully developed region then velocity is maximum.

The outlet of the pipe temperature/velocity contours are given as Figs. 9 and 10. Express that the surrounding or wall of the pipe temperature recorded 272 k or (−1 $^\circ{\rm C}$). When the temperature of flowing water is 278 k. The temperature of the water flow is maximum to the fully developed region of the pipe. Now the temperature of the water gradually decreases at exit point, as shown in Fig. 11. As a result, the water temperature dropped. The lowest temperature is recorded. Display that the surrounding or wall of the pipe temperature recorded 278 k or (−1 $^\circ{\rm C}$). When the temperature of flowing water is 272 k. The velocity of the water flow is maximum to the fully developed region of the pipe. Now the velocity of the water gradually decreases at exit point, as shown in Fig. 12. As a result, the water velocity dropped. The lowest velocity is recorded at exit point.

Fig. 9

Outlet temperature profile, v = 0.425 m/s

Fig. 10

Outlet velocity profile, v = 0.425 m/s

Fig. 11

Outlet temperature profile, v = 0.425 m/s, Inlet Tw (K) = 278 k, Wall of the Tp (K) = 272 k

Fig. 12

Outlet velocity profile, v = 0.425 m/s, Inlet Tw (K) = 278 k, Wall of the Tp (K) = 272 k

4 Conclusion

The study developed the model of the simulation and design of water circular pipe. The following points are the concluded from the study as:

• 1. The result shows that the wall of the temperature of the pipes are recorded as (−1 $^\circ{\rm C}$), (−5 $^\circ{\rm C}$). The flowing water temperature is (4 $^\circ{\rm C}$). Water velocity is v = 0.425 m/s $.$ The inlet region of the pipe the temperature of the water decreased due to the surrounding as well as inner sides of the pipe both negative temperatures. The inlet region is typical of the internal flow regime. In this region, the nearly viscous upstream flow converges and enters the pipe. The temperature remains uniform in the fully develop region while it start to decrease gradually at the out let region.

• 2. The velocity of the water decreased due to the surrounding as well as inner sides of the pipe both negative temperatures. When the water flow in a pipe reached a fully developed region the velocity of the water increased. Velocity increased because of pressure decreases because the pressure is inversely proportional to velocity. It is recommended that our powerhouse pipes be fitted at 10 feet under the earth. The temperature is slightly maximum in the winter season.