HVAC MODULE

Heating, Ventilation & Air Conditioning Design and Engineering

Gibbs & Cox, Inc. has an experienced design and engineering HVAC team, which is capable of providing a wide spectrum of services. Our services include:

Design of Collective Protection System (CPS) HVAC systems for Nuclear, Biological and Chemical survival
Heating and cooling load calculations
Pressure drop calculations
HVAC noise calculations
Developing computer programs to interface with databases and HVAC CAD models to automate heating and cooling load analyses and pressure drop calculations
Equipment selection and preparation of specifications
Preparation of installation and fabrication drawings
Equipment specification, proposal evaluation, and selection
Corrosion control

Gibbs & Cox, Inc. experience in the field of HVAC relies on an integrated engineering and design approach. The development of an HVAC design by Gibbs & Cox, Inc. can be broken down into four major categories. They are the preparation of Heating and Cooling Load Calculations and System Analysis, the preparation of an HVAC diagram and associated Equipment List, the preparation of HVAC Arrangement, Construction and Detail Drawings, and the preparation of Pressure Drop Calculations.

The design requirements of a ship are established using the unique HVAC Design Criteria Manual (DCM) for the ship and the Ship Specifications and any other pertinent contractual documents such as Government Furnished Equipment Information (GFI). If a DCM or Ship Specification is not available, Gibbs & Cox, Inc. can develop such documentation for the specific ship mission requirements. Once the HVAC requirements of the ship are established, Gibbs & Cox, Inc. develops the HVAC Diagram and performs the Heating and Cooling Load Calculations and System Analysis either manually or automatically, using the NAVSEA software package HVACCPSS as enhanced by Gibbs & Cox, Inc.

HVACCPSS, interfaces with an Engineering Product Model (EPM) Relational Database (RDB) which is used as an aide in the determination of the requirements for cooling and heating compartments aboard ships. The program calculates the steady state heat transfer that takes place between a given compartment and the adjacent compartment via the common boundaries. Incorporated into these calculations are the heat gains from sources internal to the compartment such as equipment, hot pipes, and personnel. HVACCPSS also determines HVAC system loads and equipment requirements. More specifically the program computes steady state temperatures of non-treated compartments, selects bulkhead and deck thermal insulation, computes compartment boundary transmission loads, computes lighting loads, compartment/equipment heating and cooling loads, and determines compartment flow requirements and HVAC equipment sizes.

Since its initial development, Gibbs & Cox, Inc. has enhanced and modified HVACCPSS to suit specific requirements unique to the different flights of the DDG51 Class ships. In the same manner, HVACCPSS can be enhanced to suit the requirements of different type vessels including submarines.

Interface programs were created by Gibbs & Cox, Inc. to extract the data from the RDB and prepare the necessary input files for HVACCPSS. The interface programs are grouped together under one software package called HVAC Heat loads and they process various types of data such as compartment data, HVAC Design Criteria, compartment boundary data, heat sources, and HVAC system data and sizes.

Gibbs & Cox, Inc. creates 2-D CAD HVAC diagrams showing diagrammatic HVAC system arrangements, indicating spaces served, air flow quantities and HVAC equipment. In addition, HVAC equipment lists are prepared providing the necessary engineering equipment data.

Gibbs & Cox, Inc. has a vast level of experience in the preparation of HVAC detail design drawings. An HVAC arrangement, construction and detail drawing would typically consist of standard details, fabrication details for shipyard manufactured equipment such as filter housings and louvers, installation details, ductwork fabrication sheets, and parts lists. Gibbs & Cox, Inc. has a considerable amount of experience in the creation of these drawings both manually and electronically. Gibbs & Cox, Inc. is also capable of extracting a 2-D drawing from the 3-D CAD models.

The last step in the HVAC design process as followed by Gibbs & Cox, Inc. is the preparation of the pressure drop calculations. A program named FNCALC was developed by Gibbs & Cox, Inc. as a design tool for calculating pressure losses in HVAC systems. The internal logic and procedures of FNCALC are in accordance with the NAVSEA procedures specified in DDS 3801-2, "Pressure Losses of Ventilation Fittings". FNCALC input file is comprised of five data sections. They are Velocity Control Data (specifies velocity limitations), Project Restrictions (specifies minimum allowable duct diameter), System Control Data (system description), Section Control Data (section description), and Fitting Data (fitting descriptions). With the proper use of various input parameters, it can accommodate any type fitting or terminal. FNCALC produces a well-organized and easy to read output report with warnings to the user to help in balancing the system. The input is easily manipulated to allow the user to be able to change duct sizes or add orifice plates until the system is balanced.

As part of the DDG51 program, a new HVAC system was introduced that would provide for protected areas of the ship to allow for a safe haven from Nuclear, Biological and Chemical (NBC) attacks. This system was called a Collective Protection System (CPS) which was a high pressure HVAC system using HEPA filtration of incoming air. Gibbs & Cox, Inc. was an instrumental part in the development of this technology and continues to play a role in all new designs for the marine industry.