Refrigeration Past, Present and Future // W.9.5
No one has a crystal ball to predict the future but considering history and current needs of the market allow some predictions with reasonable certainty. Past Cooling with ice has been around for thousands of years and the Romans, known to bring ice and snow from the Alps to cool their wine, gave
Today’s Technology – Ideal service tool for refrigeration applications // W.9.6
Over the last few decades, we have witnessed monumental changes in the world of technology and how it affects our everyday life. Email, texting and social networks have drastically changed the way we communicate with each other. Business happens 24 / 7 in the wired world. One industry that has not kept pace is
Understanding Ethernet – Topologies // W.5.2
Introduction Communications is one of the most dynamically changing industries. We are surrounded by continually evolving, state-of the-art technology (wifi, smart phones, satellite TV, GPS) Advanced methods of communication have filtered into many industries and revolutionized their processes and procedures. Understanding the advantage of utilizing Ethernet communications is important in
Understanding Ethernet Communication – Glossary // W.5.5
# 10Base2 10Base5 10BaseF 10BaseT # 10Base2 Ethernet specification for thin coaxial cable, transmits signals at 10 Mbps (megabits per second). Maximum distance of 185 meters per segment. (Obsolete) 10Base5 Ethernet specification for thick cable. Transmits signals at 10 Mbps (megabits per second). Maximum distance of 500 meters per segment. (Obsolete) 10BaseF
Understanding Ethernet – Cabling // W.5.3
Network Media – Cable The network media is part of the physical layer of a LAN network as defined by the OSI Open Systems Protocol Reference Model, see Table 1. It is the medium through which the information is passed from one device in the network to another. Although wireless
More Fans or Fewer? // W.2.1
More and more often, Variable Frequency Drives (VFDs) are used for control of fans and compressors in HVACR systems. The benefits are well documented and industry acceptance is such that most electric utilities offer substantial monetary incentives (rebates) when they are used. Federal, state and some local governments are also
Frost and Defrost: How it happens and why it is needed // W.1.1
Refrigeration is used to assure proper storage temperature of food products. This is most often accomplished by using the vapor compression cycle. In this technique, refrigerant vapor is compressed by a compressor, condensed into a liquid in a con-denser by the rejection of heat, expanded by a restrictive device, and
Electricity 101 // W.9.4
Introduction Traditional forms of power include muscle (human and animal) wind, water and steam. However, our modern world is based on the availability of electricity to power our machines, heat and cool our homes, and preserve and cook our food. A basic knowledge of electricity is critical to understanding how heating, ventilating, air conditioning and
Understanding Ethernet Communication – Networks // W.5.1
Networks The underlying structure of communications is a network. A network consists of two or more computers that are linked together to provide shared access to file servers, printers, or to electronic communications. The computers can be linked through phone lines, cables, satellite, radio waves or infrared light beams. There
Basic Thermodynamics For Refrigeration and Air Conditioning – Part 1 // W.9.1
Introduction Thermodynamics, as with most concepts in science and physics, is most accurately described using mathematical equations. However, simple explanations, although not perfectly accurate, are sufficient to convey the information needed to understand everyday experiences. This paper is an attempt to simplify these concepts. Thermodynamics simply describes the movement of heat. Thermodynamics is derived from thermo,
Basic Thermodynamics For Refrigeration and Air Conditioning – Part 2 // W.9.2
This simple system shows the application of the Second Law. The compressor A adds energy to the refrigerant, and it becomes hot, just the way a hand operated tire pump does. Since the compressed refrigerant is hotter than the air blowing across the condenser B , the heat will flow to the cooler air.
Basic Superheat, Saturation and Subcooling // W.9.3
An appreciation of the terms superheat and saturation is the key to understanding and troubleshooting air conditioning and refrigeration systems. Illustrations in this document show closed vessels for simplicity, but real systems consist of heat transfer surfaces (condenser and evaporator), a compressor and a restriction device. Goals By the end of this lesson you will
Understanding Ethernet Communication – Protocols // W.5.4
Protocols All of us are familiar with protocols for human communication, society’s rules about appearance, speaking, listening and understanding. These rules govern different layers of communication. They work to help us successfully communicate. Similarly, in the computer world, a protocol is a set of rules that governs communications between the