CONCLUSIONS

 

After completing this report we conclude that the experiment is a success, with all the objective set is achieve with flying colors. This is done with the aid of the lab instructor and the lab assistant.

 

The conclusion that we made that with an increased of speed of the pump it will cause the properties and characteristic to varied accordingly which in turn effect the overall efficiency, and with the increased of speed it is relevant that the efficiency also increased. The maximum operating condition is at 90% pump speed, where the efficiency is 40% at 1.7 m³/s capacity this is called BEP.

 

We need to keep in mind that this is an experiment and the value could not be achieved due to some unavoidable factor such as the condition of the experiment where the apparatus is not in a good working  condition and the experiment is conducted not under a standardize condition.

 

Overall the students that participate in the experiment got the general idea of the experiment.

 

 

 

PERSONAL CONCLUSION

 

 

The performance of a centrifugal pump can be shown graphically on a characteristic curve. A typical characteristic curve shows the total dynamic head, brake horsepower, efficiency, and net positive Suction head all plotted over the capacity range of the pump.

 

Non-dimensional curves which indicate the general shape of the characteristic curves for the various types of pumps. They show the head, brake horsepower, and efficiency plotted as a percent of their values at the design or best efficiency point of the pump.

 

The head curve for a radial flow pump is relatively flat and that the head decreases gradually as the flow increases. Note that the brake horsepower increases gradually over the flow range with the maximum normally at the point of maximum flow

 

The performance or characteristic curve of the pump provides information on the relationship between total head and flow rate. There are three important points on this curve.

 

1. The shut-off head, this is the maximum head that the pump can achieve and occurs at zero flow. The pump will be noisy and vibrate excessively at this point. The pump will consume the least amount of power at this point.

 

2. The best efficiency point B.E.P. this is the point at which the pump is the most efficient and operates with the least vibration and noise. This is often the point for which pump’s are rated and which is indicated on the nameplate. The pump will consume the power corresponding to its B.E.P. rating at this point.

 

3. The maximum flow point, the pump may not operate past this point. The pump will be noisy and vibrate excessively at this point. The pump will consume the maximum amount of power at this point.

 

Sometimes the characteristic curve will include a power consumption curve. This curve is only valid for water, if the fluid has a different density than water you cannot use this curve. However you can use the total head vs. flow rate curve since this is independent of density.

Typical centrifugal pump characteristic curve.

 

If your fluid has a different viscosity than water you cannot use the characteristic curve without correction.

DISCUSSIONS

 

The experiment is conducted to determine centrifugal pump performance characteristic by for several set of speed centrifugal pump. Efficiency is the benchmark of our experimental and theoretical result.

 

We gain the efficiency by the mathematical representations that were given to us by the lab instructor. Which in turn realize by our data that we gather in the experimental stage namely the torque, the elevation difference (water height), pump suction and delivery pressure.

 

From the result obtain we proceed to the graph section via calculation equation given.

 

For 50% of pump speed

We plot the graph of capacity Q (m³/s) versus the Pump Head (m), the graph show that the head pump gradually decreased with the increased of capacity.

 

Next we plotted the graph for capacity Q (m³/s) versus Break Horse Power (BHP), here the line clearly show that with the increase of capacity the horsepower also increased simultaneously except for the final point, this may due to the condition of the machine.

 

Then with the previous graph obtain we then plotted the graph capacity Q (m³/s)versus efficiency (η dimensionless), here the graph exhibit a concave down nature, with the max point at approximately at 1.2 m³/s capacity which give a max efficiency of 35%.

 

For 75% of pump speed

As we observed the graph of capacity Q (m³/s) versus the Pump Head (m), it show that the head pump decreased with the increased of capacity.

 

Next for the graph of capacity Q (m³/s) versus Break Horse Power (BHP), here the line clearly show that with the increase of capacity Q the horsepower increased proportionally.

 

With both the above graph obtain we now plotted the graph capacity Q (m³/s) versus efficiency (η dimensionless), here the graph follow the same nature as the previous speed but the maximum efficacy had increased to 36% at the capacity of 1.8 m³/s capacity.

 

For 90% of pump speed

Here the graph of capacity Q (m³/s) versus the Pump Head (m), the graph show that the head pump decrease as usual but some reading show that capacity value is not relevant to any mathematical function yet we still follow the procedure of the experiment. We found out that the maximum value of capacity the line is not at the minimum value of the pump head reading,

 

For the graph for capacity Q (m³/s) versus Break Horse Power (BHP), the graph follow the virtue of its previous speed that with the increase of capacity Q the horsepower also increased but the final few points does not comply to this. The final four points which posses the max value occur before the final and maximum value of the capacity.

 

For the last graph where capacity Q (m³/s) versus efficiency (η dimensionless), graph show a similar form as its predecessor but as all the graph that we plot on the 90% pump it is a bit distort but the value of the efficiency is the greatest among the three speeds which is 40%maximum efficiency at 1.7 m³/s capacity. 

 

Our discussion leads us to this assumption as why that the graph is distorted at several speed of pump which is definite the apparatus and the machinery is not in a perfect condition. We can’t really point to any severe parallax error because the reading is gathered from the machine interface directly. This is prove with the lab assistant ask us to not set the pump speed to 100% and the apparatus for gathering the turbine speed is also not in a well operation condition.

 

The only possible errors that could come from any member of the group is slight misreading of the dial but it still in a acceptable value.

 

Understanding of group member is clearly projected on the calculation and graph generation.

 

The outcome of the experiment is to give a first hand experience of what we will be learn in Fluid Mechanic II (KJM492) thus relate it together,

 

 

PERSONAL DISCUSSION

Even though I personally prepare this lab report, I would like to elaborate it for better understanding of both party. I gather this from the lab coordinator, fluid mechanics lecturer and from other suitable source.

 

The maximum volume flow rate through a pump occurs when its net heat is zero H=0, this flow rate is called the pump free delivery achieved when there is no flow restriction at the pump inlet or outlet. In other word there is no load on the pump. At this operating point. volume flow rate is large but H is zero, the pump efficiency is zero because there no useful work. At the other extreme, the shutoff head is the net head that occurs when the volume flow rate is zero achieved when outlet port of the pump is block off. Under these conditions, H is large but volume flow rate is zero. pump efficiency is also zero. Between the two the pump’s net head may increase from its shutoff value somewhat as the flow rate increases, but H must eventually decreased to zero as volume flow rate increases to its delivery value. The pump’s efficiency reaches its maximum value somewhere between he shutoff condition and the free delivery condition. This is called best efficiency point (BEP).

 

 

 

Other error that may occur are from cavitations where there is  a non uniform flow which cause the pressure gradient to shift, this is comment in pump. Also, viscosity also would affect the reading if we would change the fluid in the experiment.

 

GRAPHS

Graphical Results for Test 1.Pump speed = 50%.

 

Graph 1.0 Capacity Versus Pump Head.

Graph 1.1 Capacity Versus Brake Horsepower.

Graph 1.2 Capacity Versus Efficiency.

 

Graphical Result for Test 2. Pump speed = 75%.

 

Graph 1.3 Capacity Versus Pump Head.

Graph 1.4 Capacity Versus Brake Horsepower.

Graph 1.5 Capacity Versus Efficiency.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Graphical Result for Test 3. Pump speed = 90%.

 

           

Graph 1.6 Capacity Versus Pump Head.

 

Graph 1.7 Capacity Versus Brake Horsepower.

Graph 1.8 Capacity Versus Efficiency.

 

Graph 1.9 Performance Characteristic at 50% and 1400 rpm

 

 

Graph 2.0 Performance Characteristic at 75% and 2150 rpm

 

Graph 2.0 Performance Characteristic at 90% and 2600 rpm

 

SAMPLE OF CALCULATION

 

At test 1:          Water Height = 0.053 mm

Pump Speed = 50 %

RPM = 1400 = 146.61 rad/s

 

 

Pump Head:

 

hp = (p2 – p1)/ρg

                 = [48.28×10³-519.93] / (1000) (9.81)

                 = 4.87m

 

Brake Horsepower:

 

Wshaft = Tω

              = 0.9 × 146.61

              = 131.95 hp

 

Power:

 

Pf = ρgQhp

                  = (1000) (9.81) (0.92 ×10ֿ³) (4.87)

                = 43.95 watt

 

Pump Overall Efficiency:

 

       η   = Pf / Wshaft      x 100

                        = (43.95 / 131.95) x 100

                                    = 33.31 %

RESULT

Test 1. Pump Speed = 50%

RPM = 1400

          = 146.61rad/s

No.	Water height, h(mm)	Inlet Pressure, P(Psi)	Discharge Pressure, P(Psi) x 103	Torque, T(N.m)	Capacity, Q x 10-3(m3/s)	Pump head , hp (m)	Brake Horsepower Wshaft (bhp)	Power WHP Watt,	Pump overall efficiency, η (%)
1	0	0	55.17	0.5	0	5.62	73.31	0	0
2	0.053	519.93	48.28	0.9	0.92	4.87	131.94	43.95	33.31
3	0.060	588.60	41.38	1.0	1.25	4.16	146.61	51.01	34.80
4	0.064	-627.84	34.48	1.1	1.47	3.58	161.27	51.03	32.10
5	0.067	-657.27	27.59	1.1	1.67	2.88	161.27	47.18	29.26
6	0.069	-676.89	20.69	1.2	1.76	2.18	175.93	37.64	21.40
7	0.071	-696.51	13.80	1.2	1.92	1.48	175.93	27.88	15.85

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

                                                                                                                                                                                          

 

 

 

Test 2. Pump Speed = 75%

RPM = 2150

         = 225.15 rad/s

No.	Water height, h(mm)	Inlet Pressure, P(Psi)	Discharge Pressure, P(Psi) x 103	Torque, T(N.m)	Capacity, Q x 10-3(m3/s)	Pump head, hp (m)	Brake Horsepower Wshaft (bhp)	Power WHP Watt,	Pump overall efficiency, η (%)
1	0	0	126.41	0.90	0	12.89	202.64	0	0
2	0.057	0	112.62	1.80	1.10	11.48	405.27	123.88	30.57
3	0.067	-657.27	98.62	2.00	1.63	10.12	450.30	161.82	35.94
4	0.073	-716.13	84.82	2.20	2.05	8.72	495.33	175.36	35.40
5	0.076	-745.56	71.03	2.35	2.25	7.32	529.10	161.57	30.54
6	0.079	-774.99	57.24	2.45	2.48	5.91	551.62	143.78	26.07
7	0.080	-784.80	43.45	2.50	2.58	4.51	562.88	114.15	20.28
8	0.081	-794.61	29.66	2.50	2.62	3.10	562.88	79.68	14.16

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Test 3. Pump Speed = 90%

RPM = 2600

         = 272.27 rad/s

No.	Water height, h(mm)	Inlet Pressure, P(Psi))	Discharge Pressure, P(Psi) x 103	Torque, T(N.m)	Capacity, Q x 10-3(m3/s)	Pump head, hp (m)	Brake Horsepower Wshaft (bhp)	Power WHP Watt,	Pump overall efficiency, η (%)
1	0	0	186.21	1.40	0	18.98	381.18	0	0
2	0.068	-667.08	165.52	2.70	1.72	16.94	735.13	285.83	38.89
3	0.074	-725.94	144.83	3.10	2.12	14.84	844.04	308.63	36.57
4	0.078	-765.18	124.14	3.20	2.42	12.73	871.26	302.21	34.69
5	0.079	-774.99	103.45	3.30	2.48	10.62	898.50	258.37	28.80
6	0.083	-814.23	82.76	3.40	2.80	8.52	925.72	234.03	25.30
7	0.083	-814.23	62.07	3.30	2.80	6.41	898.50	176.07	19.60
8	0.082	-804.42	41.38	3.30	2.72	4.30	898.50	114.74	12.77
9	0.081	-794.61	20.69	3.40	2.65	2.19	925.50	56.93	6.15