Goal: When you have finished this laboratory exercise you will understand
- the role of various components of a pumping system in transporting liquid foods and their influence on pumping energy requirements
and you will learn
- the key components of a pumping system that influence its energy requirements
- the change in pumping energy requirements with respect to mass flow rate of the liquid food and the total length of the piping system
Pumping of liquid food is a common operation in a food processing plant. To transport liquid foods from one location to another, a pumping system is designed that consists of a pump, pipes and fittings such as elbows, tees, and valves. A wide variety of pumps, pipes and fittings are used in the industry. Some of the commonly used pumps and fittings are as follows:
Centrifugal pumps are one of the most common pumps used in the food industry. Following diagram shows various components of a centrifugal pump.
Various types of fittings such as valves, bends and reducers are used in pumping fluid from one location to another.
Flow is diverted using various types of connectors including a tee shown below.
Positive displacement pumps are used to pump highly viscous foods such as mayonnaise or tomato paste.
The following diagram shows the various parts of a positive displacement pumps.
An experiment to measure pumping energy requirements requires first setting up a liquid transport system. Typically, the system will involve a pump, fittings and possibly some storage tanks.
A laboratory experiments involves the following steps:
1) Set up a pumping system involving a pump, fittings and other process equipment.
2) Measure the diameter of pipe, total elevation of pumping, mass flow rate of juice, number and type of fittings used and length of the pipe.
3) Operate the system with the desired flow rate and determine energy requirements.
In the virtual experiment, you will be able to select either steel pipe of sanitary pipe. The other choices will include pipe diameter, elevation of pumping, mass flow rate, length of pipe, and any number and types of fittings. The results give theoretical pumping requirement in Watts.
Design of pumping systems involves conducting an energy balance. For this purpose we use Bernoulli equationwhere z is height, P is pressure ,v is velocity, W is work done by the pump and F is friction energy losses.
The pipe length and fittings contribute to the friction energy loss. We will examine these in the experiment.
In this laboratory exercise, you obtained the energy requirements of the total pumping system for a given set of input values.
From different experimental trials, determine the change in the pumping energy requirement for different system design parameters, such as pipe diameter, pipe length, elevation, and number and type of fittings.
Similarly, determine the effect of changing mass flow rate on pumping energy requirements for any given set of system parameters.
- How does the flow rate affect the energy requirements of pumping?
- How does the total pipe length affect energy requirements for pumping?
- What is the effect of pipe fittings on the energy requirement of pumping?
- Which pipe fittings have the most dominant effect on energy requirements of pumping?
- Barbosa-Canovas, G.V., Ma, L., and Braletta, B. (1997). "food Engineering Laboratory Manual," Technomic Publishing Company, Inc. Lancaster.
- Munson, B.R., Young, D.R., and Okiishi, T.H. (1998). "Fundamentals of Fluid Mechanics," John Wiley and Sons, New York.
- Singh, R.P. and Heldman, D.R. (2009). "Introduction to Food Engineering," 4th ed., Academic Press, London.
- Smits, A.J. (2000). "A Physical Introduction to Fluid Mechanics." John Wiley and Sons, Inc., New York.