Effects of R134a Saturation Temperature on a Shell and Tube Condenser with the Nanofluid Flow in the Tube Using the Thermal Efficiency and Effectiveness Concepts

Élcio Nogueira

doi:10.4236/wjnse.2021.111001

Abstract

The work’s objective is to analyze the influence of the saturation temperature of the R134a refrigerant on the thermal performance of a shell and tube type condenser, with water and aluminum oxide (Al2O3) nanoparticles flowing into the tube. For analysis, the heat exchanger is subdivided into three regions: subcooled liquid, saturated steam, and superheated steam. The shell and tube heat exchanger assumed as the basis for the study has 36 tubes, with rows of 4 tubes in line and three passes into the tube in each region. The parameters used to analyze the performance are efficiency and effectiveness, through variations of quantities such as saturation temperature, the nanofluid’s mass flow rate, fraction in the nanoparticles’ volume, and the number of passes in the tube in each region of the heat exchanger. The obtained results demonstrate that the efficiency is relatively high in all the analyzed situations. In each saturation temperature, the effectiveness can be increased by introducing fractions of nanoparticles in the water or increasing the number of passes in the tube.

Highlights

Gaurav Thakur and Gurpreet Singh [7] argue that the injection of air bubbles, which contributes to increasing the level of turbulence in the flow, is a technique that improves the thermal efficiency in shell and tube heat exchanger
The work’s objective is to analyze the influence of the saturation temperature of the R134a refrigerant on the thermal performance of a shell and tube type condenser, with aluminum oxide (Al2O3) nanoparticles flowing into the tubes
The fluid inlet temperature in the tubes is equal to 25 ̊C, and the refrigerant inlet temperature is equal to the saturation temperature (Tsat)

Summary

Introduction

Gaurav Thakur and Gurpreet Singh [7] argue that the injection of air bubbles, which contributes to increasing the level of turbulence in the flow, is a technique that improves the thermal efficiency in shell and tube heat exchanger They perform an experimental analysis by injecting air bubbles at the tube entrance with water-based nanofluids (Al2O3) and volumetric fractions equal to 0.1% and 0.2%. Das [11] argue that Prandtl, Reynolds, and Nusselt for nanofluids influence the convective heat transfer coefficient and that the pumping power depends on the Reynolds number They perform a comprehensive analysis to assess the effects on nanofluids’ thermal and hydraulic performance as a function of variations in density, specific heat, thermal conductivity, and viscosity. They conclude that nanoparticles’ addition increases viscosity and thermal conductivity moderately and that specific heat and density change modestly

Objective

Methodology

Saturated Steam

Subcooled Liquid

Superheated Steam

Conclusions