Pack

Pack or packs may refer to:

Places

People

Air cycle machine

An air cycle machine (ACM) is the refrigeration unit of the environmental control system (ECS) used in pressurized gas turbine-powered aircraft. Normally an aircraft has two or three of these ACM. Each ACM and its components are often referred as an air conditioning pack. The air cycle cooling process uses air instead of a phase changing material such as Freon in the gas cycle. No condensation or evaporation of a refrigerant is involved, and the cooled air output from the process is used directly for cabin ventilation or for cooling electronic equipment.

History

Air cycle machines were first developed in the 19th century for providing chilling on ships. The technique is a reverse Brayton cycle (the thermodynamic cycle of a gas turbine engine) and is also known as a Bell Coleman cycle or "Air-Standard Refrigeration Cycle".

Technical details

The usual compression, cooling and expansion seen in any refrigeration cycle is accomplished in the ACM by a centrifugal compressor, two air-to-air heat exchangers and an expansion turbine.

Playing card

A playing card is a piece of specially prepared heavy paper, thin cardboard, plastic-coated paper, cotton-paper blend, or thin plastic, marked with distinguishing motifs and used as one of a set for playing card games. Playing cards are typically palm-sized for convenient handling.

A complete set of cards is called a pack (UK English), deck (US English), or set (Universal), and the subset of cards held at one time by a player during a game is commonly called a hand. A pack of cards may be used for playing a variety of card games, with varying elements of skill and chance, some of which are played for money (e.g., poker and blackjack games at a casino). Playing cards are also used for illusions, cardistry, building card structures, cartomancy and memory sport.

The front (or "face") of each card carries markings that distinguish it from the other cards in the pack and determine its use under the rules of the game being played. The back of each card is identical for all cards in any particular pack to create an imperfect information scenario. Usually every card will be smooth; however, some packs have braille to allow blind people to read the card number and suit.