Heat and Mass Transfer Lab 1
Heat & Mass Lab 1: | | |
2/10/2011
2/10/2011
Executive Summary
This experiment was conducted using a heat transfer unit. Many relationships were obtained and calculated from the observed results. To name a few; the log mean temperature difference, heat transfer coefficient, Reynolds, Nusselt and Graetz numbers.
The main focus of this experiment is the heating and cooling of the oil fluid. This was achieved using the heating component in the heat exchanger and water flowing from the tap. Varying temperatures and flow rates were used via adjusting the heating component and the control valve respectively to determine the effect each had on various relationships.
The system was found to have a Reynolds number in the laminar region, an overall heat transfer coefficient of around 140W/m2.K, and a Nusselt and Graetz number of approximately 14 and 1500 respectively. A reduced flow rate used in the following trials led to a lower value in many of the derived results.
In subsequent trials, where a reduced flow rate is used, many of the calculations such as heat transfer, Reynolds number and other values were much lower. This is because many of the calculations are a function and directly proportional to the flow rate which is the main driving force in this experiment.
The first generated plot of heat transfer coefficients and mean oil velocity shows that the heat transfer coefficient is directly proportional to and increases with the oil velocity. The second plot of Nusselt number against Graezt number shows both increases as the other increase.
This experiment can only give a rough indication to the expected values with this setup. Many sources of error exist and the largest being experimental equipment and materials. Due to equipment constraints, a larger portion of heat is lost from the system to the environment. Not only has this, but measurements of temperature and water flow rate constantly fluctuated making it difficult to obtain precise
2/10/2011
2/10/2011
Executive Summary
This experiment was conducted using a heat transfer unit. Many relationships were obtained and calculated from the observed results. To name a few; the log mean temperature difference, heat transfer coefficient, Reynolds, Nusselt and Graetz numbers.
The main focus of this experiment is the heating and cooling of the oil fluid. This was achieved using the heating component in the heat exchanger and water flowing from the tap. Varying temperatures and flow rates were used via adjusting the heating component and the control valve respectively to determine the effect each had on various relationships.
The system was found to have a Reynolds number in the laminar region, an overall heat transfer coefficient of around 140W/m2.K, and a Nusselt and Graetz number of approximately 14 and 1500 respectively. A reduced flow rate used in the following trials led to a lower value in many of the derived results.
In subsequent trials, where a reduced flow rate is used, many of the calculations such as heat transfer, Reynolds number and other values were much lower. This is because many of the calculations are a function and directly proportional to the flow rate which is the main driving force in this experiment.
The first generated plot of heat transfer coefficients and mean oil velocity shows that the heat transfer coefficient is directly proportional to and increases with the oil velocity. The second plot of Nusselt number against Graezt number shows both increases as the other increase.
This experiment can only give a rough indication to the expected values with this setup. Many sources of error exist and the largest being experimental equipment and materials. Due to equipment constraints, a larger portion of heat is lost from the system to the environment. Not only has this, but measurements of temperature and water flow rate constantly fluctuated making it difficult to obtain precise
References: Chua H.T (n.d), Laminar/viscous flow heat transfer experiment, lab manual distributed in Heat and Mass Transfer (CHPR2432) at the University of Western Australia on 1st August 2011, p1-2, 6-8 Coulson, J. et al. (1999) Coulson & Richardsons ' Chemical Engineering Volume 1 - Fluid Flow, Heat Transfer and Mass Transfer, 6th ed. China: Butterworth Heinemann, p.211-222, 655-660 Engineer’s Edge (n.d.) Log Mean Temperature Difference, [online] Available at: http://www.engineersedge.com/thermodynamics/log_mean_temp.htm [Accessed: 7th October 2011]. Engineer’s Edge (n.d.) Overall Heat Transfer Coefficient, [online] Available at: http://www.engineersedge.com/heat_transfer/overall_heat_transfer_coef.htm [Accessed: 7th October 2011]. Heat and Mass Transfer (CHPR2432) Lab 1 Manual (2011) Laminar/Viscous Flow Heat Transfer Unit H970. [image online] Available at: https://webct.uwa.edu.au/webct/urw/lc103130001.tp0/cobaltMainFrame.dowebct [Accessed: 6th October 2011]. Incropera, F. et al. (2001) Fundamentals of Heat and Mass Transfer, 5th ed. Australia: Wiley, p.512-520. Perry & Green (1997) Perry’s Chemical Engineers’ Handbook, 7th ed. Australia: McGraw Hill, p-5-17 – 5-26