Category Archives for Liquid Recirculation

When To Choose Liquid Recirculation

The advantages and disadvantages of liquid recirculation were listed in Section 8.3. Liquid recirculation competes against flooded-coil evaporators and direct expansion. The advantages of liquid recirculation become dominant in lowtemperature installations and where there are multiple evaporators, particularly if they … Continue reading

14. May 2018 by Jim
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Energy Analysis Of Gas Pumping

The comparison of mechanical pumping and gas pumping that will be presented in Section 8.16 will contend that greater mechanical energy must be expended in a gas-pumping system than in a system with mechanical pumps. While the overall merits of … Continue reading

14. May 2018 by Jim
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Gas Pumping – The Controlled Pressure Receiver

What is probably the most popular of the gas-pumping arrangements uses a controlled-pressure receiver (CPR), one version of which is shown schematically in Fig. 8.26. A key concept is that the receiver no longer operates at essentially the condensing pressure, … Continue reading

14. May 2018 by Jim
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Pumping Liquid Refrigerant With Gas Pressure – The Two Pumping Vessel System

As an alternative to mechanical pumps, liquid refrigerant may be circulated by means of gas pressure. There are several different concepts and methods of control in industrial use, but a common element is a pumping vessel held at low pressure … Continue reading

14. May 2018 by Jim
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The Liquid Distribution System And Pump Selection

Usually the path of the liquid mains and branches is dictated by the geometric configuration of the plant. After the layout is established, the designer must position the shutoff valves and decide what pressure relief provisions must be made in … Continue reading

14. May 2018 by Jim
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Piping Feature Surrounding The Pump

Some basic objectives in designing and installing the pump and its inlet piping are: • provide generous NPSH • install two pumps, one of which is standby • provide a region for oil to separate from ammonia and be drained … Continue reading

10. May 2018 by Jim
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Centrifugal Pump – Hermetic

What are called hermetic refrigerant pumps are actually semihermetic, because many elements can be dismantled for servicing. What is distinctive about the pump is that there are no moving metal parts, such as the shaft, that must be sealed to … Continue reading

10. May 2018 by Jim
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Centrifugal Pump – Net Positive Suction Head

The single most effective method of preventing cavitation in the operation of a centrifugal pump when handling refrigerants close to their saturation condition is to provide an adequate amount of net-positive-suction head (NPSH). The NPSH is defined as the difference … Continue reading

10. May 2018 by Jim
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Centrifugal Pump – Open Type

The centrifugal pump functions by first setting the liquid in motion and then converting the velocity into pressure. This procedure is achieved with a pump as shown in Fig. 8.14 where a rotating impeller is contained within a progressively expanding … Continue reading

09. May 2018 by Jim
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Positive Displacement Pump

Positive-displacement pumps are usually of the gear type where the meshing of gears conveys the liquid around the periphery of the gears, as in Figure 8.11a or in a combination of internal and external flow9 as in Figure 8.11b. When … Continue reading

09. May 2018 by Jim
Categories: Liquid Recirculation | Comments Off on Positive Displacement Pump

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