Numerical Analysis of Transient Response in a Single-Pass Cross flow Heat Exchanger

Crossflow heat exchangers are commonly employed in process critical applications in industries. A heat exchanger can be subjected to flow or temperature perturbation during its regular operation. It should be noted that a heat exchanger would require a finite time to overcome such perturbations. In this study, the transient response of a single-pass crossflow heat exchanger with variable inlet temperatures and mass flow rates was determined. Herein, the analysis of the transient performance of cross flow heat exchangers is conducted on a dimensionless basis. In every instance, the energy balance equations were solved using an explicit finite difference method. Numerical predictions were obtained for cases where both the fluids were subjected to step changes in inlet temperature, coupled with step mass flow rate change of the fluids. The analysis can be readily extended to study different flow circuiting and inlet conditions

Performance of Pure Crossflow Heat Exchanger in Sensible Heat Transfer Application

All process industries involve the usage of heat exchanger equipment and understanding its performance during the design phase is very essential. The present research work specifies the performance of a pure cross flow heat exchanger in terms of dimensionless factors such as number of transfer units, capacity rate ratio, and heat exchanger effectiveness. Steady state sensible heat transfer was considered in the analysis. The matrix approach that was established in the earlier work was used in the study. The results were depicted in the form of charts, tables, and performance equations. It was observed that indeterminately increasing the number of transfer units past a threshold limit provided very marginal improvement in the performance of a pure cross flow heat exchanger. Likewise, flow pattern in a heat exchanger is usually assumed either as mixed or unmixed. However, due to various operating conditions, partially mixed conditions do exist. This work considers partially mixed conditions in the tube side of the heat exchanger. The correction factor for heat exchanger effectiveness was developed to accommodate partially mixed flow conditions in the pure cross flow heat exchanger

Design of a Heat Sink for an Electronic Component in ABB Drive using Different Types of Fins

This paper considers an analytical approach in the design of a passive heat sink for an ABB electrical drive. The heat sink is intended to dissipate a certain amount of heat energy and to maintain the surface temperature of an electronic communication board at the prescribed temperature. The maximum size of the heat sink is known due to the existing space constraint. This paper details the step by step procedure in the development of a passive heat sink that functions based on the natural convection. Two commonly used fins such as rectangular plate fins and rectangular pins fins were considered for the project. A parametric study was considered wherein a relationship was developed between the convection heat transfer coefficient and the air flow. Likewise, the impact of convection heat transfer coefficient was seen on the rate of heat transfer and the fin geometry

Economize air conditioning system by pre-cooling fresh intake air

As the demand for electricity continues to increase, a significant amount of fossil fuels are being burned to meet our needs. One of the major contributors to high electricity consumption, accounting for almost 20% of total generated electricity, is the air conditioning system and cooling systems. Given its significant impact on the environment, it is essential to improve its efficiency and to reduce its energy consumption. The project is focused on enhancing the efficiency of air conditioning system while minimising its energy consumption. An air conditioning system typically utilizes recirculated air along with some amount of fresh air. While humans require a certain quantity of fresh air for proper functioning, the required amount varies based on the air conditioned space. In India, as the ambient conditions are usually warmer, mixing of outdoor air with recirculated air leads to additional cooling and higher energy consumption. To reduce excessive energy consumption, it will be beneficial to reduce the ambient air temperature prior to mixing process. Precooling intake air using a plate heat exchanger is considered in this project work. The overall reduction in energy consumption by pre-cooling fresh air is 13%

Sensible Performance Analysis of Multi-Pass Cross Flow Heat Exchangers

In this paper, a steady state sensible performance analysis of a multi-pass cross flow exchanger exhibiting various flow circuiting is considered. Counter cross flow, parallel cross flow and pure cross flow (where the flow circuiting is neither in parallel nor in counter flow) are considered in this paper. A previously developed matrix approach is used to study the heat exchanger performance at each individual pass. The equations required for modeling a cross flow heat exchanger for each flow arrangement are presented. Thereafter, a baseline heat exchanger geometry was selected and performance of the heat exchanger for each flow circuiting was described. As expected, the best thermal performance was seen in a counter cross flow heat exchanger and the performance of pure cross flow was intermediate between that of a parallel and a counter cross flow heat exchanger

Sensible Performance Analysis of Multi-Pass Cross Flow Heat Exchangers

In this paper, a steady state sensible performance analysis of a multi-pass cross flow exchanger exhibiting various flow circuiting is considered. Counter cross flow, parallel cross flow and pure cross flow (where the flow circuiting is neither in parallel nor in counter flow) are considered in this paper. A previously developed matrix approach is used to study the heat exchanger performance at each individual pass. The equations required for modeling a cross flow heat exchanger for each flow arrangement are presented. Thereafter, a baseline heat exchanger geometry was selected and performance of the heat exchanger for each flow circuiting was described. As expected, the best thermal performance was seen in a counter cross flow heat exchanger and the performance of pure cross flow was intermediate between that of a parallel and a counter cross flow heat exchanger

Design of Thermal Energy Storage System

The paper concentrates on the design of a sensible thermal energy storage system. In a process plant, steam is used to create vacuum in a pressure vessel. Thereafter, steam is exhausted to the environment in a carbon steel pipe. A thermal energy storage system is designed to partially absorb the wasted energy and to store the energy in a tank. Dowtherm, a popular heat transfer fluid is chosen as the energy storage medium. A bolt-on heat exchanger is used to transfer heat from the steam pipe. The heating mechanism, and thermal energy storage is modelled using MATLAB. The basic energy storage system is designed by employing engineering standards, alternatives, and constraints