Preconditioned Air:

Background

It is well recognized throughout the industry that preconditioned air systems are the most advantageous sources of comfort air for parked aircraft. The benefits for using PCA, versus using the aircraft on-board auxiliary power unit (APU), have been proven time and again both on economic and environmental grounds.

When correctly designed and implemented, PCA systems can allow the aircraft's APU to be shut down during gate operations thereby reducing ramp noise and congestion, fuel consumption and emissions, as well as APU maintenance costs. The PCA process consists of taking ambient air, cooling or heating the air as necessary to supply to the aircraft cabin for the purpose of maintaining a comfortable passenger cabin temperature.

PCA systems can be divided into two major categories:

In designing a POU system, one must first realize that it is a much better alternative than the mobile system because the POU system produces lower noise, has zero gas emission, and does not contribute to ramp congestion. The POU unit, however, still requires a significant amount of maintenance. This is due to the many complex moving components required for each POU unit. The POU system offers low initial capital cost but requires high energy usage throughout the system life cycle. The POU system is more suitable for small facilities with five or less gates to service.

Central Chiller Plant System with Gate Mounted AHU's

A central PCA system heats or cools a heat transfer medium, usually an ethylene glycol / water (EG/W) mixture, at a centralized plant and then distributes this medium to air handling units located at each gate. These air handling units in turn provide conditioned air to the cabin by blowing 100% outside air through the AHU coils. The typical central plant consists of chillers, boilers or heat exchangers, pumps, tanks, condensers, cooling towers, and associated electrical power and control equipment.

Central System Design Considerations

Typically, a central system will have a greater initial capital investment than the POU system. However, it can significantly reduce the operation and maintenance cost over the life of the system compared to POU alternatives. Central systems have fewer refrigeration compressor circuits and associated controls such that less maintenance is required. Furthermore, industrial grade equipment permits the selection of more energy efficient equipment. The gate equipment for central systems are lighter and require less maintenance because the compression and refrigeration circuits are located at the central plant. In addition, the central system can be designed with thermal storage and diversity capabilities to better match even the most fluctuating system loads. Thermal storage can also be implemented integrally as an energy savings technique. In general, central PCA systems prove to be more suitable for medium to large facilities with at least five or more gates. The economic benefits increases as the size of the system increases.

Preconditioned air has been one of ASE's core competencies since the company's inception. The principals of ASE have a total of over 50 years in the design-build industry, and a total of over 20 years in the field of aviation ground support systems which include preconditioned air. We have evaluated, designed, constructed, and commissioned PCA systems throughout the world. These designs have been comprised of both POU systems as well as central systems. ASE designed and managed the construction of a central and POU system at the Los Angeles International Airport, a central system at Dallas/Ft. Worth International Airport and a central system at the O'Hare International Airport. ASE actively participates in various professional and airport organizations in an effort to keep up with current technology and design methods in order to provide the best solutions to our customers. For example, ASE co-authored the PCA section of the Air Transport Association's (ATA) Facility Planning Guidelines.

ASE is always at the forefront of technology when it comes to design and engineering. We utilize sophisticated computer modeling software to analyze the necessary cooling and heating requirements of particular aircraft at specific local conditions. This program allows the engineer to enter site specific weather data, aircraft size and type, and published aircraft load requirements such that the total load data sheet can be generated for design. The program input parameters include ambient temperature, humidity, and the number of passengers and crew. Aircraft mix served at each aircraft parking position is also an important design consideration. At ASE we actively maintain American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE) published weather data and aircraft specific data in our databases such that we are capable of producing load and design data sheets rapidly and accurately. Where applicable, we also maintain our customer design conditions and requirements for comparison with ASHRAE design conditions.

Design Codes and Standards

ASE takes tremendous pride in providing complete services for PCA systems. We strive to provide our clients with unmatched services from the feasibility study phase to final commissioning phase of the project. The following represents the process in which ASE can provide these unmatched values to our customer either in separate phases or all together.

ASE's Services

Feasibility Analysis / Field Surveys

ASE has extensive field experience necessary to visit a project site and be able to determine what it takes to bring the client's vision into reality.

Budgets / Schedules

The budgeting and scheduling process represents one of the most critical project tasks at ASE in order to complete the project not only on time but also on budget. This is one of the areas where ASE's attention to details can have the utmost positive cascading effect on the overall project.

Conceptual Design

The wide diversity of technical and business experiences shared among the ASE team, ensure reliable and accurate conceptual designs.

Detailed Design and Engineering

Our solid combined background in mechanical and electrical engineering plus HVAC/R experience allows us to approach PCA design and engineering problems in the most creative and efficient manner. We pay close attention to specification compliance in accordance to codes and regulations in our design, and utilize state-of-the-art sophisticated computer systems to perform and check complex calculations. Doing the job right the first time and every time is the goal for each of our designers and engineers.

Equipment Procurement

We can assist the customer to develop equipment and construction specifications in accordance with the design requirements, perform bid evaluations, and order equipment.

Equipment Contract Administration

After the equipment procurement process takes place we can help our customers to manage each equipment contract, perform shop drawing review, equipment testing, and assure timely delivery for the project.

Construction Management

At ASE we pride ourselves in turning the conceptual design into the final product. Comprehensive well planned integrated scheduling and project management provide highly accurate construction monitoring and favorable results; these are the hallmarks of the AERO Systems managed projects.

Start-Up / Commissioning

At ASE we realize the importance and need of minimizing system downtime for our customers. Therefore, we strive to provide the most responsive services in bringing the system on line by dedicating a start-up / commissioning team to the project site and establishing a detailed start-up procedure before the start-up begins.

Most of all, ASE approaches PCA projects from concept to completion in the true sense of teamwork and partnership with our customers. We provide unmatched project management services that allow our customer to focus on their core business competencies without compromising their support systems.

We invite you to take a closer look at our quality designs and services and discover why AERO Systems Engineering is...

"The logical source for aviation ground support system designs, and installations and services."