Module 1 What is Refrigeration and Air Conditioning-converted PDF

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COURSE MODULECOURSE CODE: RACModule 1Week 1: February 1-6, 202 | 2nd Semester, S. 2020- 2021IntroductionThis course deals with the basic concepts, theories and principles related to Domestic and Commercial Refrigeration and Air-conditioning. Students are engaged in basic troubleshooting and servicin...

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COURSE CODE: RAC Module 1 Week 1: February 1-6, 202 | 2nd Semester, S.Y. 2020- 2021

Introduction

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This course deals with the basic concepts, theories and principles related to Domestic and Commercial Refrigeration and Air-conditioning. Students are engaged in basic troubleshooting and servicing of domestic RAC and commercial RAC units.

Intended Learning Outcomes • • •

Define RAC, Identify different types of RAC units, Definition of RAC terms

Topic 1 Air conditioning, or more specifically, heating, ventilating, air ventilating, air conditioning, and refrigeration (HVAC&R), was first systematically developed by Dr. Willis H. Carrier in the early 1900s. Because it is closely connected with the comfort and health of the people, air conditioning became one of the most significant factors in national energy consumption. Most commercial buildings in the United States were air conditioned after World War II. In 1973, the energy crisis stimulated the development of variable-air-volume systems, energy management, and other HVAC&R technology. In the 1980s, the introduction of microprocessor based direct-digital control systems raised the technology of air conditioning and refrigeration to a higher level. Today, the standards of a successful and cost-effective new or retrofit HVAC&R projects include maintaining a healthy and comfortable indoor environment with adequate outdoor ventilation air and acceptable indoor air quality with an energy index lower than that required by the federal and local codes, often using off-air conditioning schemes to reduce energy costs. What is Refrigeration and Air Conditioning? ▪

Refrigeration and air conditioning is used to cool products or a building environment. The refrigeration or air conditioning system (R) transfers heat from a cooler low-energy reservoir to a warmer high-energy reservoir (see figure 1).

Refrigeration ▪ ▪

relates to the cooling of air or liquids, thus providing lower temperatures to preserve food, cool beverages, make ice, and for many other applications. The process of removing heat

Air conditioning ▪ ▪

includes space cooling, heating, humidifi cation, dehumidifi cation, air filtration, and ventilation to condition the air and improve indoor air quality. A form of air treatment whereby temperature, humidity, ventilation, and air cleanliness are all controlled within limits determined by the requirements of the air conditioned enclosure.

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There are several heat transfer loops in a refrigeration system as shown in Figure 2. Thermal energy moves from left to right as it is extracted from the space and expelled into the outdoors through five loops of heat transfer: ▪ Indoor air loop. In the left loop, indoor air is driven by the supply air fan through a cooling coil, where it transfers its heat to chilled water. The cool air then cools the building space. ▪ Chilled water loop. Driven by the chilled water pump, water returns from the cooling coil to the chiller’s evaporator to be re-cooled. ▪ Refrigerant loop. Using a phase-change refrigerant, the chiller’s compressor pumps heat from the chilled water to the condenser water. ▪ Condenser water loop. Water absorbs heat from the chiller’s condenser, and the condenser water pump sends it to the cooling tower. ▪ Cooling tower loop. The cooling tower’s fan drives air across an open flow of the hot condenser water, transferring the heat to the outdoors.

DIFFERENT TYPE OF COMMERCIAL REFRIGERATORS: 1. Reach-in Freezers And Refrigerators These are storage units perfect for back of the house operations. You can acquire both glass door reach-in units and solid door reach-in units in Dutch style half or in full length doors. The storage capacity of reach-in units is determined by cubic feet and they also have multiple sections.

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2. Walk-in Refrigerators If you plan to open a restaurant that requires a large amount of storage space, then you should consider investing in walk-in refrigerators. For optimal organization, many operators set up commercial shelving operations inside their walk-in freezers. These walk-in units are great for storing juices, alcohol, bulk or boxed items.

3. Serve Over Counter These units are perfect if you plan to open a meat outlet, café or grocery store. They make the displayed items much more appealing by using bent or level glass. Serve-over-counters are similar to counter-top display refrigerators; the only difference is that serve-over-counter units don’t have a glass that fully covers the food products. Customers can get what they want without asking the servers. 4. Under counter Refrigerators These units function similarly to upright reach-in units. The only difference is that they are much shorter and they can fit into much smaller spaces. So if your commercial kitchen needs a unit to store few products that can be used on asneeded basis then an under counter refrigerator would be appropriate.

5. Bar Refrigerators There are many types of bar refrigerators such as back bar refrigerators, plate chillers, keg coolers, etc. Bar refrigerators are normally designed with a black vinyl or a stainless steel exterior to give the under counter bar area a more streamlined look.

6. Pastry Or Bakery Display These units can either have a traditional wooden finish or stainless steel curved with glass. It usually has the front part covered with glass so that customers can view all the bakery and pastry products.

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7. Refrigerated Prep Tables These units are used in the preparation area or cook line in the commercial kitchen. There are two major versions of the refrigerated prep tables: pizza prep tables and sandwich/salad tables. Cold storage wells keep ingredients cold and fresh. This refrigerator has drawers that store prepared sauces or dressings. The biggest difference between a pizza table and a salad table is probably the depth of the cutting board. For a pizza table, the cutting board is deeper and can easily accommodate a wide diameter pizza.

DIFFERENT TYPES OF AC UNITS: There are six different types of air conditioners that are each designed for a different space/reason. These six types of AC units are the basic central AC, ductless, window unit, portable unit, hybrid, and geothermal. 1. Central Air Conditioners A central air conditioner combines the evaporator, condenser, and compressor in a single unit that is placed on a roof or a concrete slab near the foundation. From the unit, ducts running through the exterior wall or roof draw air from inside the house and return cooled air indoors. This type of air conditioner can also be combined with a set of heating coils or a natural gas furnace inside the building. 2. Ductless, Mini-Split Air Conditioners This is a good choice for houses that do not have ductwork. The ductless, mini-split systems combine an outdoor compressor and condenser with one or more indoor airhandling units. These units are mounted on the wall with blowers attached. Tubing connects the indoor and outdoor units and circulates refrigerant between them. Each room in your home will have a separate unit that cools just that room, similar to a window unit. These can be installed without tearing up walls, and allow the temperature to be controlled independently in each room. They can be more energy efficient, but are more expensive if you’re cooling an entire house. 3. Window Units These are the most common types of AC units for single rooms. All of the components are enclosed in a single box with a single thermostat gauge that is fitted in a slot made in the wall or window sill where the unit sits.

4. Portable Units

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This is similar to a window system, but it can be moved from room to room. It’s self-contained and freestanding on the floor so you can move it from room to room or apartment to apartment. It only uses an outlet to power on and a window to funnel out the exhaust air.

5. Hybrid Air Conditioner Hybrid type of AC unit systems alternate between burning fossil fuels and using electricity to save money and energy while running your system. In the summer, the heat pump works as it normally does, pulling heat from your home and distributing it outdoors. In the winter, your hybrid heat pump system works in reverse, pulling heat from the outside environment and distributing it into your home. 6. Geothermal Heating and Cooling As a newer method of heating and cooling, geothermal technology is able to extract the heat from below the ground and transfer it into your home. A geothermal coil is installed deep in the ground and can be used to heat and cool your home. In the winter, heat is extracted from the Earth; in the summer, heat is extracted from your home and distributed back into the ground. This is very sustainable, energy efficient, and provides a longer lifespan than other options.

TECHNICAL TERMS: BTU - British thermal unit. A unit of heat energy - approximately the amount of energy needed to heat one pound of water by one degree Fahrenheit. dBA – a unit for measuring sound power or pressure, deciBel on the A scale. Capacity – the ability of a heating or cooling system to heat or cool a given amount of space. For heating, this is usually expressed in BTU’s. For cooling, it is usually given in tons. Compressor – the pump that moves the refrigerant from the indoor evaporator to the outdoor condenser and back to the evaporator again. The compressor is often called “the heart of the system” because it circulates the refrigerant through the loop. Condenser – a device used to condense a refrigerant thereby rejecting the heat to another source, typically an air cooled or water cooled condenser.

Cassette – a fan coil unit that fits mainly in the ceiling void with only a diffuser plate visible, diffuses conditioned air in one, two, three or four directions. HVAC – heating, ventilation and air conditioning. Inverter system – Constantly alters fan and motor speeds. This enables faster cooling of a room, and the inverter air conditioner doesn’t have to switch itself on and off to maintain a constant temperature.

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kw – standard measurement of heat or power, 1kw = 1000 watts = 3412Btu/hr = 860kcal. Load Calculation – a mathematical design tool used to determine the heat gain and heat loss in a building so that properly sized air conditioning and heating equipment may be installed. Refrigerant – a substance that produces a refrigerating effect while expanding or vaporizing. Reverse cycle – the reverse cycle air conditioner internally reverses its operation to provide heating or cooling, as required. Split System – a central air conditioner consisting of two or more major components. The system usually consists of a compressor-containing unit and condenser, installed outside the building and a non-compressor – containing air handling unit installed within the building. This is the most common type of system installed in a home. Zoning – the practice of providing independent heating and/or cooling to different areas in a structure. Zoning typically utilizes a system controller, zoning dampers controlled by a thermostat in each zone, and a bypass damper to regulate static pressure in the supply duct.

TRY THIS!

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References •

https://blog.leaseq.com/equipment-leasing/different-types-of-commercialrefrigerators#.YCRHwLBKjIU

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https://www.mytrustedcontractor.com/types-ac-units/

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Module in Refrigeration and Air Conditioning http://www.brainkart.com/article/Technical-Terms-of-Refrigeration-and-AirConditioning_5678/

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