Substantial Benefits
A Pre-Cooling System provides a number of benefits:
1. Reduced Energy Costs
The reduced demand and energy usage leads to reduced demand and usage charges and substantially lower energy costs.
2. Reduced Maintenance Costs
By lowering head pressures and extending compressor life, maintenance costs can be greatly lowered. High head pressures can greatly reduce compressor life. Conversely, by lowering peak head pressures through evaporative fogging, compressor life can be greatly extended.
3. Increased Peak Cooling Capacity
By reducing the saturated liquid temperature, the system will increase peak cooling capacity by upwards of 20%.
4.Reduced Energy (kWh) Usage
The system will reduce kWh over the entire ambient temperature range from 75 F and higher. Depending on the actual ambient conditions, kWh savings of 11% to 20% can be expected.
5. Reduced Peak Demand (kW)
The system will reduce kW over the entire ambient temperature range from 75 F and higher. Again, depending on actual ambient conditions, peak kW savings of up to 30% can be expected.
FAQ's
Is it a good investment?
Yes. A Pre-Cooling system will usually pay for itself within two years and continue to reduce energy and maintenance costs for years to come.
What is evaporative fogging?
Utilizing "thermal dynamics", water is passed through a pump, raising its pressure to 1,000psi, and then sent through high-pressure piping and fogging nozzles to atomize the water droplets to 10 microns or less. When the water mist is injected into an air stream moving across an air-cooled condenser (condenser air), it is “flash-evaporated" and the temperature of the condenser air is lowered.
Is evaporative fogging a new practice?
No. Evaporative fogging started more than 25 years ago for outdoor cooling in such applications as patios and outdoor restaurants. Today, we supplie evaporative fogging systems for industrial cooling, wine barrel storage, dust suppression, odor control, greenhouse climate control, power turbine inlet fogging, cold storage facilities, wet rooms, special effects, poultry, cattle and horse cooling, fire suppression, and air-cooled refrigeration, air conditioning condensers, and more.
What are the differences between evaporative condensers, water towers, and the fogging system?
All three systems dissipate heat through evaporation. The manner in which they go about doing this, however, is decidedly different:
- With evaporative condensers, water is sprayed across condenser tubes. As air passes over the tubes, the water evaporates, cooling the tubes and their contents.
- With cooling towers, water is passed through a heat exchanger in which it absorbs heat. The heat is dissipated in the cooling tower as air is blown across the water.
- With the a fogging system, a water mist is injected into the condenser air stream. As the mist evaporates, the temperature of the condenser air is lowered. As the now cool condenser air is blown across the condenser coil, the coil rejects more heat and the performance of the air-cooled system is improved.
What evidence exists that fogging condenser air will improve the performance of air-cooled condensers?
Studies show substantial savings. In addition, an independent study commissioned by Southern California Edison recently validated the savings to be achieved from evaporative fogging. In addition, manufacturers’ data sheets suggest that air cooled systems perform better under cooler ambient conditions.
Why does cooling system energy usage increase as the ambient temperature rises?
There are three primary reasons:
- As the ambient temperature rises, the condenser cannot reject as much heat, therefore the head pressure also rises. This increases the compression ratio (head pressure/suction pressure) so the compressors draw more power when they run.
- As the head pressure increases, the saturated liquid (refrigerant) temperature rises and system cooling capacity falls. Therefore, the system must run longer to satisfy the load so it uses more energy.
- In applications where higher ambient temperatures increase the load in the space to be cooled, the cooling system must run longer so energy use increases.
Can it be retrofitted without major modifications?
Evaporative condensers and cooling towers are typically installed pre-construction; The system is most often retrofitted to existing systems. While evaporative condensers and cooling towers could also be retrofitted to existing systems, the process is much more difficult, invasive, and costly. By comparison, our system does not require that the condenser be shut down or modified. It is simply installed in a suitable location, water piping is run to the condensers, and the system turned on.
What benefits are derived when condenser air is cooled through evaporative fogging?
As the temperature of the condenser air falls, the condenser is able to reject more heat, so the head pressure is reduced. This lowers the compression ratio so the compressors draw less power when they run.
As the head pressure falls, the saturated liquid temperature also falls and cooling capacity increases. Therefore, the system does not have to run as long to satisfy the load and energy use is reduced.
Reduced head pressures lengthen compressor life, increase cooling reliability, and lower maintenance costs.
Will fogging condenser air reduce peak demand (kW), energy usage (kWh), or both?
Both. Since the compressors will draw less power when they run because of lower head pressures, demand will be reduced. Since the cooling capacity of the system will be increased, the compressors will run less, so energy usage will be reduced.
Will the energy savings be relatively constant over the entire range of ambient conditions?
No. The greatest temperature reductions will occur under the hottest and driest ambient conditions. During those periods, the percentage of energy savings will be greatest. However, in the course of a year there are many more hours when the conditions are far more moderate, so the greatest kWh savings will be accumulated during those periods.
Can it cause coil corrosion?
The high pressure micro-orifice nozzle and installation design is done in a manner that helps ensure flash-evaporation, thereby reducing moisture contact.
