Experimental study on centrifugal pumps energy labelling in Iran

Transcription

1 IO Conference Series: arth and nvironmental Science xperimental study on centrifugal pumps energy labelling in Iran To cite this article: S Derakhshan et al 2012 IO Conf. Ser.: arth nviron. Sci View the article online for updates and enhancements. Related content - Research on rotational speed to the influence of pump as turbine S S Yang, F Y Kong, W M Jiang et al. - Optimal design of axial hydro turbine for micro hydropower plants S Derakhshan and N Kasaeian - On high efficiency operation of contrarotating axial flow pump with rotational speed control toward effective energy saving L L Cao, S Watanabe, T Imanishi et al. This content was downloaded from I address on 01/05/2018 at 06:42

2 xperimental study on centrifugal pumps energy labelling in Iran S Derakhshan 1, Abdolahnejad and M Buzari 2 1School of Mechanical ngineering, Iran University of Science & Technology, Narmak, Tehran, 16846, IRAN 2Berkeh ump, Tehran, IRAN -mail: shderakhshan@iust.ac.ir Abstract. The main goal of the present study was developing the energy label instruction for small centrifugal pumps. First the types of energy labels which are popular in the world especially three types of energy labels were introduced and discussed, two of which belongs to uropean United and the other one is assigned to Iran. Modified Iran labelling procedure with reasons was criticized and presented as a new approach in the present study. In the next step, e a standard test rig was established for testing of the small centrifugal pumps. A standard centrifugal pump named and was selected as the case studies. The selected pumps were test in the test rig and then labelled using selected methods. Finally the results considered and discoursed. 1. Introduction As the growing use of energy and the restriction of energy resources, an attempt for monitoring energy consumption has been become an obligation in recent years. nergy label is one of the useful methods in promoting energy efficiency that play its role in three main sections: ncourages the producers to improve their product performance by making competition between them ncourages the distributors and retailers to offer products with higher efficiency. Gives consumers enough information to choose the most efficient and the best product available in the market. In general, three important types of energy labels exist: [1] endorsement label comparative labels label containing only information In fact, the factors we need to label a device are: Reference energy Consumption Calculated energy Consumption Reference energy consumption to calculated energy consumption ratio is nergy efficiency index, and the label category will be determined next. umps are considered as the Industry heart and a significant proportion of energy consumption is allocated to this part. ublished under licence by Ltd 1

3 Therefore, optimization of energy consumption in this sector is essential. One of the approaches to deal with this problem is using energy labels and increasing the quality of products using the competitive marketing ideas. This outline has been proposed in Iran since 1997, and a standard document has been developed for centrifugal pumps [2]. In general, larger pumps have higher productivity, it should be taken into account in ranking pumps on basis of energy efficiency: the ranking procedure should be independent of the size (or input power) of the pumps in the same specific speeds. In the present study, first the types of energy labels which are popular in the world especially three types of energy labels were introduced and discussed, two of which belongs to uropean United and the other one is assigned to Iran. Modified Iran labelling procedure with reasons was criticized and presented as a new approach in the present study. In the next step, e a standard test rig was established for testing of the small centrifugal pumps. A standard centrifugal pump named and was selected as the case studies. The selected pumps were test in the test rig and then labelled using selected methods. Finally the results considered and discoursed. 2. nergy labelling in pumps Specific speed for each pump is indicator of its family. Thus for a correct comparison between the energy consumption of pumps, comparison should be done in a family. As shows in the figure 1, efficiency depends on specific speed and flow rate (size of the pump). In the other words, in same specific speeds, larger pumps have higher efficiencies! This should be considered in labelling procedure. Figure 1.Relation between efficiency, specific speed and discharge.[3] 2.1. nergy efficiency index of Iran[2] The energy consumption index in centrifugal pumps is maximum acquirable efficiency which the best efficiency point discharge is defined. erformance Assessment criterion of internal pumps is the specifications published in sales catalogues by manufacturers and some foreign producers. Figure 2 shows this labelling procedure. It can be seen that there is not any attention to specific speed and expected pump efficiency nergy efficiency index of urope in 2001[4] The following equation is derived that must be used to determine the energy efficiency: calc I (1) ref (2) hydraulic According to the statistical considerations, a pump at all times will not work in the maximum capacity, Therefore the annual energy consumption is obtained as below: 2

4 % % % tref calc % 0 (3) where t ref = usage time duration for pump (usually considered to be one ear) Now we can calculate the energy efficiency index for the desired device. After that we should compare obtained values with values given in table 1 to determine device energy efficiency class. Figure 2. Iranian labelling standard chart. [2] Table 1. nergy fficiency Class in uropean 2001 method [4] nergy efficiency class nergy efficiency index A B C D F G I< I< I< I< I< I< I 2.3. nergy efficiency index in urope in 2005[4] In this method the energy efficiency index is defined with the following equation: I L, avg (4) followed first ref will be determine and then how to determine the L,avg. As productivity of pumps is depended on pump size, the power consumption of a pump will depend on both hydraulic power and size of the pump. So for calculating reference power consumption of a pump with a certain size, a relation between hydraulic power and maximum power consumption was made. The relation is only focusing on maximum power consumption because power consumption at partial load is taking into account elsewhere. To build this relation the maximum power consumption has been calculated for the majority of pumps on the market. Results of this investigation are shown below in equations (4) and (5): ref 2.21 W (5) ref hydraulic 55 Q H W hyd 2.73 max. (6), max 3

5 where: hyd,max : Maximum hydraulic power in W; Q: flow (m 3 /s); H: pressure (m). The linear relation gave unrealistic reference power consumptions for small pumps with a hydraulic power less than 20 W. Therefore the reference power calculation was change to the equation (6): ref 0.39 e hyd,max W (7) hyd, max 1 the cal measured and calculated cal,avg, then energy efficiency index is calculated in equation (7): I cal, avg (8) The energy efficiency index (I) for circulator has to be calibrated to the 7 levels in the U A-G label. This calibration is shown in table Suggested method In order to improve the methods used in Iran labelling, modifications are presented. As mentioned in the introduction and according to the figure (ns), for comparing the efficiency of two pumps, specific speed should be noted. But in Iran labelling, this point has not been properly considered. Therefore it should be chosen method that considers effect of the specific speed. This correction is shown in figure 3. In This figure for the number of approved manufacturing pumps in the market (based on their catalogue) efficiency vs. discharge graph was plotted. Clearly in this graph the effect of specific speed can be seen. Table 2.nergy fficiency Class in 2005 uropean method [5] nergy efficiency class A B C D F G ref nergy efficiency index I< I< I< I< I< I< I Figure 3. The effect of specific speed on efficiency of pumps. 4

6 As a suggestion, separated standard curves can be formed for each specific speed range. In this method, for a specific speed range certain graphs are produced, such as figure 4 and figure 5. In these diagrams, slopes of diagonal lines are determined based on mean slope of constant specific speed curves. For any given discharge range, the average slope can vary. The distance between adjacent diagonal lines is 5.0%. This division is quite innovative. The two graphs in figure 4 and figure 5 are drawn respectively for two special specific speed ranges from 10 to 15 and 20 to 25. Because of different ranges, the expected efficiencies are different. As an example, a pump with a discharge of Q bep =50 m 3 /hr and ns=25 that classified in class A must have at least efficiency equal to 70%. While another pump at the same discharge but with ns=15 that classified in class A must have at least efficiency equal to 60%. This difference is due to the hydraulic machinery nature and not because of their quality. Figure 4. chart labelling for ns=10-15 Figure 5. chart labelling for ns= Test setup 3.1. ump selection: Two small centrifugal pumps were selected as the case studies from market with close discharge and various heads: pump type and pump type Table 3 shows the hydraulic characteristics of selected pumps according to their manufacturing catalogues. Table 3. Hydraulic characteristics of tested pumps ump type Discharge (m3/hr) Head (m) Specific speed fficiency at B ower (KW) % % xperimental setup Test rig size and volume of the reservoir with respect to maximum flow and testing standards were selected. ipe line size of test rig was 2 inches. This circuit includes intake valve, pump, motor, the suction and discharge pressure gages, water pipes and measurement reservoir (figure 6) Measurement procedure[6],[7] Head: to get the pump head, pressure in the inlet and outlet of the pump with the help of scorpion shaped manometer was measured. Discharge: in order to measure discharge of pump in any flow rate, volume and required time for filling measurement reservoir were measured. 5

7 ower: the pump inputs power by measuring the torque on the shaft and rotational speed of shaft was calculated. For this purpose, the motor was suspended and then rotational speed and torque were measured (figure 7). Finally, with having net power input, net power output and efficiency, energy efficiency index was calculated. According to this information, energy label class was determined. Figure 6.Schematic of test rig Figure 7.Torque measurement part of test rig 4. Results The pumps head and hydraulic efficiency diagrams derived from experimental have been shown in figure nergy labeling using different methods According on different method, after measuring the consumption power and calculating reference power, the studied pump will be classified. In table 4 results of labelling based on different methods are shown. Based on this comparison, uropean (2005) and suggested method can be considered as a better procedure in labelling. These two methods consider effect of specific speed correctly. Obviously for more accurate method in labelling, the more research and experimental studied are needed. Figure 8. performance curves for centrifugal pumps based on test 6

8 Figure 9. performance curves for centrifugal pumps based on test 5. Conclusions In the presented paper, three different methods for energy labelling in centrifugal pumps was investigated. And for correctness of Iran energy labelling standard, a new method was presented. The suggested method considers effect of specific speed on efficiency and energy label. Two pumps were tested and labelled based on different method. Results were shown and effect of specific speed was considered. Based on comparison, uropean (2005) and suggested method can be considered as a better procedure in labelling. These two methods consider effect of specific speed correctly. Obviously for more accurate method in labelling, the more research and experimental studied are needed. Table 4. Labelling based on different methods for tested pumps Methods Iran nergy fficiency Class (test) nergy fficiency Class (catalogue) F C 2001 uropean G G G 2005 uropean C C B C Suggested D D A D References [1] Lloyd H and Melissa D 2004 nergy labelling and standards programs throughout the world The National Appliance and quipment nergy fficiency Committee (Australia, July 2004) [2] Institute of Standards and Industrial Research of Iran, Centrifugal, mixed flow and axial pumps, Method for Measuring of nergy Consumption and nergy Labelling Instructions, 1st.edition. [3] 2010 Centrifugal ump Handbook 3rd edition (Winterthur, Switzerland) [4] U SAV II roject romotion of nergy fficiency in Circulation umps, June 5, 2001 especially in Domestic Heating Systems, Task 2:Technical / economical analysis final report 7

9 [5] Bidstrup N, Hunnekuhl G, Heinrich H and Andersen T 2003 Classification of Circulators, (uropump report) pages [6] Michael A C 2009 Industrial Flow Measurement (West Yorkshire:University of Huddersfield Repository) [7] Hydraulic performance acceptance tests ISO 9906 standard, grades 1 and 2 nglish version. 8