Liquid Pressure Amplifiers Improve Efficiency
Of Air Conditioning and Refrigeration

With the rising costs of energy, many companies are evaluating the efficiency of their air conditioning and refrigeration systems. If you are one of them, you may want to make your system less costly to operate without having to buy an entirely new system. A Liquid Pressure Amplifier may be just what you're looking for...

Back in the 1940s when the design of most present-day air conditioning and refrigeration systems originated, electricity costs were low. Equipment designers often sacrificed energy efficiency to make a product that had a less expensive purchase price. This equipment design, without the use of variable head pressure controls, wastes 20-40% of the electrical power used. Liquid Pressure Amplifier technology can save a good portion of this wasted energy.

An air conditioning or refrigeration system has four basic parts, which operate in the following basic manner:

The compressor begins with a warm gaseous refrigerant, such as Freon or ammonia, and mechanically compresses it, raising the temperature and pressure of the gas.
The hot gaseous refrigerant is transferred to the condenser, where some of the heat is released to the outside air, causing the refrigerant to condense to a liquid form.
From the condenser, the liquid refrigerant goes through an expansion valve where the pressure is reduced, causing the refrigerant to cool.
The cool refrigerant absorbs heat from the water or air surrounding the evaporator (sometimes called the coil), and this is where the cooling work takes place.
The warmed refrigerant converts back to a gaseous form, then return to the compressor where the whole cycle begins again.

In most systems, the compressor has to work "double duty." First it has to raise the pressure of the refrigerant high enough so it will turn back into a liquid when it cools down in the condenser. Then it also has to add enough pressure to push the liquid refrigerant from the condenser all the way to the evaporator without any refrigerant turning to a gas before it gets to the evaporator. This is where a Liquid Pressure Amplifier (LPA) comes in.

An LPA is a small pump, placed in the system between the condenser and the evaporator. This pump provides the pressure necessary to move the liquid refrigerant from the condenser to the evaporator, so the compressor doesn't have to work as hard. You save energy, and by removing some of the load from the compressor, you reduce the wear and tear on the equipment at the same time.


Normal System

In cooler weather, the outside temperature can reduce the load on your compressor, because the refrigerant doesn't need to be compressed as much to turn it into liquid form at the condenser. But this isn't the case with standard air conditioning and refrigeration systems that don't have variable head pressure controls. Instead, the condenser is sized to deliver full capacity on the hottest days, and internal pressure is maintained at that same level on cooler days. The artificially high head pressure causes the compressor to actually work harder and consume more energy than necessary on cool and moderate days.

With Liquid Pressure Amplifier technology, a control system adjusts the compressor pressure output according to outside temperatures. It is logical that cooler weather should provide you savings in the energy required by your refrigeration and air conditioning systems, and an LPA makes this possible. With an LPA, the colder the outside temperature, the greater you additional savings.


System with LPA
There are many benefits to using Liquid Pressure Amplifier technology, prompting some air conditioning and refrigeration system manufacturers to use this process on all their equipment, with many more offering to add it to equipment, if requested.

Iowa Electric is currently working with some customers to install LPA technology in their systems. As part of our energy efficiency incentive programs, we will work with you to monitor the energy savings which result from the use of LPAs. Based on the energy saved, you may be eligible to receive cash incentives to help pay for the cost of installing this energy saving equipment. The incentive is a one-time payment, but the decreased energy consumption and improved compressor performance are you benefits for years to come.

If you think a Liquid Pressure Amplifier might be right for your system, or you would like to talk to us about Iowa Electric's energy efficiency incentive programs, please call us at 1-800-822-4348, Ext. 3242.

-excerpts from Energy Insights volume 8, Jan./Feb. 1994-
published by Iowa Electric Light and Power
Ceder Rapids, Iowa
Copyright1993