Energy saving, pumps

In summary, heat-driven cycles for cooling or heat pumping can have energy saving and environmental benefits. There are also niche applications in developing countries or remote areas. Adsorption cycles using active carbons are one of a number of approaches that might be economically viable. 

Most induction ac motors are fixed-speed. However, a large number of motor applications would benefit if the motor speed could be adjusted to match process requirements. Motor speed controls are the devices which, when properly applied, can tap most of the potential energy savings in motor systems. Motor speed controls are particularly attractive in applications where there is variable fluid flow. In many centrifugal pump, fan, and compressor applications mechanical power grows roughly with the cube of the fluid flow. To move 80 percent of the nominal flow only half of the power is required. Centrifugal loads are therefore excellent candidates for motor speed control. Other loads that may benefit from the use of motor speed controls include conveyers, traction drives, winders, machine tools and robotics. 

The initial rejection of the efficient heat pump by many consumers may be well founded or not. In addition to the sound economic rationales for rejection, there may be market-impediment explanations. Consumers may have imperfect information and be unaware of the energy savings of new, efficient technologies. The transaction cost of accjuiring information and making an efficient choice may be just too high. Because of these impediments, households often fail to make investments that would actually save them money over time. 

The cost premium for a motor equipped with speed control can be substantial, sometimes costing twice that of a single-speed motor. But the energy savings from speed control can be substantial, especially for fan and pump systems. Electronic adjustable speed drives continue to become more attractive because the costs of microelectronics and power electronics technologies continue to fall as performance and energy efficiency improve. 

Measures SH and SI are hydronic water loop systems with water-to-air heat pumps. These systems also offer energy savings over the base case, but have an incremental cost over the base case. Other than the system type, these measures are the same as SE and SF, so either payback period is immediate for similar reasons. 

Proper machine cycle settings are also important for energy savings. The injection speed control system (available on new machines as an option or as a retrofit on old machines) optimizes the speeds available for specific time intervals. The injection high volume pump is available for a fixed time period and is then dropped out of the system. This time period should coincide with... 

Flickinger, W., "Energy Saving, One Pump Divert Systems", in HPM Now, (Fall 1977), HPM Corp., 820 Marion Road, Mount Gilead, Ohio 43338. 

The control valve is a variable orifice device in which the size of the orifice is adjusted to control a process variable. Consequently, the manufacturer, type, or even the size of a control valve has no effect on the energy dissipated in the control of a selected stream once the process pressure, line size, and pumps have been selected. This energy-independence of the control valve assures that continuous throttling of the flow stream is required to control a process variable. In those cases where a valve is used for shut-off or override control (not a continuous throttling device), energy savings can be realized by selecting a valve with a minimum pressure loss in the full-open position. 

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