Advantages Of Heat Exchanger

CHAPTER 1

INTRODUCTION

1.1 Introduction

Heat exchangers have always been an important part to the lifecycle and operation of many systems. A heat exchanger is a device built for efficient heat transfer from one medium to another in order to carry and process energy. Typically one medium is cooled while the other is heated. They are widely used in petroleum refineries, chemical plants, petrochemical plants, natural gas processing, air-conditioning, refrigeration, and automotive applications [7].

Shell-and-tube heat exchangers (STHEs) are the most widely type of heat exchanger used in industrial processes as in nuclear power stations as condensers, steam generator in pressurized and water reactor plants, and feed water heaters. STHEs are also

They are the first choice because of well established procedures for design and manufacturing, many years of satisfactory service, and availability of codes and standards for design and fabrication. They can be applied to various industrial processes for large range of operating conditions, such as chemical industry, power production, food processing, distillation, cryogenics, and waste heat recovery. However, it holds disadvantages like severe fouling issue in dead zones, induced tube bundle vibration, and high power consumption. Therefore, a great number of academic attentions have been to overcome the above-mentioned drawbacks [9].

Shell-and-tube heat exchangers are the most common type of thermal equipment employed in chemical process industries. This widespread use can be justified by its versatility, robustness and reliability. Despite the technological advances of other exchanger types (e.g., plate-and-frame, spiral, lamella, etc.), shell-and-tube heat exchangers will maintain a central position in industrial activities in the next years

In essence, a shell and tube exchanger is a pressure vessel with many tubes inside of it. One process fluids flows through the tubes of the exchanger while the other flows outside of the tubes within the shell. The tube side and shell side fluids are separated by a tube sheet. In these heat exchangers, one fluid flows through tubes while the other fluid flows in the shell across the tube bundle. The design of a heat exchanger requires a balanced approach between the thermal design and pressure drop [3].

Shell and tube heat exchanger design is normally based on correlations, among these; the Kern method and Bell-Delaware method are the most commonly used correlations. Kern method is mostly used for the preliminary design and provides conservative results.

Whereas, the Bell-Delaware method is more accurate method and can provide detailed results. It can predict and estimate pressure drop and heat transfer coefficient with better accuracy. The Bell-Delaware method is actually the rating method and it can suggest the weaknesses in the shell side deign but it cannot indicate where these weaknesses are. Thus in order to figure out these problems, flow distribution must be understood. For this reason, several analytical, experimental and numerical studies have been carried