University of Sunderland Faculty of Applied Sciences Department of Computing, Engineering and Technology EAT118 – ENERGY CONVERSION Assignment 2 of 2 Important Information You are required to submit your work within the bounds of the University Infringement of Assessment Regulations (see your Programme Guide). Plagiarism, paraphrasing and downloading large amounts of information from external sources, will not be tolerated and will be dealt with severely. Although you should make full use of any source material, which would normally be an occasional sentence and/or paragraph (referenced) followed by your own critical analysis/evaluation. You will receive no marks for work that is not your own. Your work may be subject to checks for originality which can include use of an electronic plagiarism detection service. Where you are asked to submit an individual piece of work, the work must be entirely your own. The safety of your assessments is your responsibility. You must not permit another student access to your work. Please ensure that you retain a copy of your assignment. We are required to send samples of student work to the external examiners for moderation purposes. It will also safeguard in the unlikely event of your work going astray. Submission Date and Time Submission Location Before 4pm, Tuesday 2nd May 2017 St Peter’s Library, Prospect Building Page 1 of 4 EAT118 Energy Conversion - Coursework 2016-2017 You must submit this report by the referred work deadline. Note that this is an individual assignment. Description An experiment has been carried out in order to investigate pipe losses caused by three different bends, a sudden enlargement, and a sudden contraction. The apparatus used in the experiment is shown schematically in Figure 1. Figure 1: Schematic of apparatus The experiment was conducted as follows. The pressure drop across each pipe feature was measured by means of piezometer tappings, located upstream and downstream of the fittings. These were connected to a multitube manometer, as shown in Figure 1, so that the pressure drop across each fitting is a differential piezometer reading, given in mm (1-2, 3-4 etc.). Readings were obtained at various flow rates Q, measured in kg/s. The results are shown in Table 1, along with the bore diameters of the smaller and larger pipes. You are required to analyse this data, with the aid of Microsoft Excel or otherwise, and derive the secondary loss coefficients associated with the three pipe bends (mitre, elbow and large radius), the sudden enlargement, and the sudden contraction. You should also compare the results with those given in relevant literature (such as lecture notes and/or text books or websites). Page 2 of 4 Table 1: Results Differential piezometer reading (mm) Mitre h1 2 154 148 126 104 90 75 53 Q (kg/s) 0.554 0.524 0.514 0.462 0.427 0.392 0.329 Elbow h3 4 113 102 93 77 64 58 40 Large Bend h9 10 62 58 55 45 39 28 22 Enlargement h5 6 -28 -26 -25 -19 -12 -14 -10 Contraction h7 8 109 100 89 71 63 52 36 Pipe diameters: 22.5 mm and 29.6 mm Read carefully the Hints section, which has information to help you calculate your answers, and the more detailed Submission Requirements section. Hints Ignoring friction and any changes in gravitational head, Bernoulli’s equation becomes: pi g Vi 2 2g pj V j2 g 2g (1) hL where i,j = refer to the values before and after a fitting (for example, i=1 and j=2 for the mitre bend) and hL is the secondary head loss caused by the fitting. In the case of the three bends, Vi = Vj = V1, where V1 is the velocity in the smaller bore pipe. This is the same velocity at positions 2, 3, 4, 5, 8, 9, and 10. Equation (1) can then be written as follows: pi g pj g hL hL hi j V12 K 2g (2) Hence, by plotting hL versus (V12/2g) using the data given for the different flow rates, you should obtain a straight line graph through the origin, with gradient K, the loss coefficient. In the case of the enlargement, Equation (1) becomes: p5 g V52 2g hL p6 g h5 V62 2g 6 hL V12 V22 2g (3) V12 K 2g In other words, you need to also account for the sudden change in velocity, when the water flows from the smaller into the larger bore pipe. Page 3 of 4 Similarly, for the contraction: hL h7 8 V22 V12 2g K V12 2g (4) Note the reversal of the squared velocity terms in Equation (4), compared to Equation (3). Submission Requirements 1. Create a table that shows Q (kg/s), V1, V2 (m/s), (V12/2g), (V22/2g) (mm), and hL (mm) for all five fittings. [20 marks] 2. Plot hL versus (V12/2g) for the mitre, elbow and large bend, on a single graph. [30 marks] 3. Plot hL versus (V12/2g) for the enlargement and contraction, on a single graph. [20 marks] 4. Estimate K for each pipe fitting, by finding the gradient of each line you have plotted. [10 marks] 5. Compare the value of K derived above with the expected value and briefly comment on your findings (a sentence or two for each will suffice). You should cite any source used that has informed your answer. [20 marks] Page 4 of 4