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Variable Air Volume (VAV) Systems

HVAC

Variable Air Volume (VAV) systems are the most widely used types of HVAC air systems for medium- and large-sized commercial building projects (projects larger than 10,000 ft2) because VAV systems are flexible, energy efficient, and provide a comfortable indoor environment. VAV systems deliver variable supply airflow at a constant temperature (typically 55°F) through the primary air duct to multiple VAV terminal units, each of which serves a separate temperature zone. Each VAV terminal unit contains a motor-operated damper that modulates the primary airflow to the zone, an inlet airflow sensor, and, in some instances, a heating coil and a small recirculating air fan.

HVAC

HVAC air systems can be either centralized or decentralized. Centralized air systems receive their cooling and heating energy from a remote central plant. Decentralized HVAC air systems contain the central heating and cooling plant equipment within the air system itself. HVAC air systems can also be constant air volume (CAV) or variable air volume (VAV). CAV systems deliver constant supply airflow at a variable temperature. VAV systems deliver variable supply airflow at a constant temperature. CAV and VAV air systems can be further subdivided into systems that condition a single temperature zone and systems that condition multiple temperature zones.

Control

Free cooling systems can generate significant savings for the owners of such systems. However, the amount of potential energy savings available depends almost totally on the overall system design and on the selection of equipment for use in the system. In general, the designer must balance higher equipment cost with greater opportunity for energy savings. Fortunately, these savings — and their associated costs —are reasonably quantifiable so that designers can make intelligent choices guided by reliable information. This article will describe Capacity Control Methods in free cooling design schemes.

Control

Cooling towers are used to dissipate heat from air conditioning or industrial process systems. Many of the air conditioning systems currently in use only operate during the summer cooling season, but there are numerous air conditioning and process systems that require cooling year-round. In some cases, the entire cooling system is required to operate during the winter. The cooling tower is required to provide the same 85° F (30° C) or colder water to the system as it does in the summer, but it does so at lower ambient temperatures. However, there are some applications designed to use the cooling tower for “free cooling”. Free cooling is when chilled water is cooled by cooling tower water through the use of heat exchangers without the use of refrigerant compressors. Free cooling can be accomplished when ambient conditions allow the cooling tower to produce “chilled water” for the system.

Commissioning, Equipments, HVAC, Piping

Stainless steel provides its superior corrosion resistance by developing a surface film of chromium oxide during the manufacturing process. In order to ensure maximum corrosion protection, stainless steel must be kept clean and have an adequate supply of oxygen to combine with the chromium in the stainless steel to form “chromium-oxide”, a protective passivation layer. Stainless steel is the most cost effective material of construction available to extend the life of a cooling tower, closed circuit cooler or evaporative condenser in HVAC-R industry.

CAD & BIM

CARRIER Autodesk® REVIT® 3D Templates:

– Airside
– Chillers
– Ductless Systems
– Packaged Indoor
– Packaged Outdoor
– Split Systems
– Variable Refrigerant Flow

Refrigeration

This article is a continuation of our older article, which was well received by users, so we decided to update the P-H Diagram list and provide you with a more complete list of the world’s commercial refrigerants.
You can easily access the high quality refrigerant chart by clicking on the refrigerants listed in the table.

Refrigeration, Softwares

The application compares different systems based on a geographical location. Pack Calculation Pro is designed to compare different system designs, control strategies and refrigerants for your refrigeration or heat pump project, by calculating yearly energy consumption, as well as Life Cycle Costing (LCC) and Total Equivalent Warming Impact (TEWI).

Refrigeration, Softwares

– Cycle analysis (process design) – comparison of one stage direct expansion cycle and one stage flooded cycle.
– System sizing – calculation of component sizes from general criteria.
– System simulation – calculating operating conditions in a system with known components.
Component calculations – calculation of – components efficiencies and outlet conditions.
– Evaluation of operation – evaluation of system efficiency.
– Process investigation – e.g. moist air calculations.

Refrigeration, Softwares

– Cycle analysis (process design)
– System sizing
– System simulation
– Component calculations
– Analysis of operating conditions
– Transient simulation (cooling of an object/room)
– Refrigerant calculations (property plots, thermodynamic & transport properties, comparison of refrigerants)
– Life cycle cost (LCC)

Equipments, HVAC, Piping, Refrigeration

A variety of liquids could be considered for Data Center applications.
When liquids are employed within separate cooling loops that do not communicate thermally, the system is considered to be air cooling. The most obvious illustration covers the chilled-water CRACs that are usually deployed at the periphery of many of today’s data centers. At the other end of the scale, the use of heat pipes or pumped loops inside a computer, wherein the liquid remains inside a closed loop within the server, also qualifies as air-cooled electronics, provided the heat is removed from the internal closed loop via airflow through the electronic equipment chassis.

Refrigeration

Good piping design results in a balance between the initial cost, pressure drop, and system reliability. The initial cost is impacted by the diameter and layout of the piping. The pressure drop in the piping must be minimized to avoid adversely affecting performance and capacity. Because almost all field-piped systems have compressor oil passing through the refrigeration circuit and back to the compressor, a minimum velocity must be maintained in the piping so that sufficient oil is returned to the compressor sump at full and part load conditions.
Several HVAC systems require field refrigeration piping to be designed and installed on-site. Examples include Condensing units, Direct expansion (DX) coil in air handlers, Remote evaporators with air-cooled chillers and Chiller with a remote air-cooled condensers. This Guide covers R-22, R-407C, R-410A, and R-134a used in commercial air conditioning systems.

Commissioning, HVAC, Piping

A 4-pipe heating and cooling plant contains both central heating and cooling equipment and is capable of delivering heating water and chilled water to the building simultaneously through four pipes (one heating water supply, one heating water return, one chilled water supply, and one chilled water return). Heating and cooling equipment within the building that is connected to a 4-pipe system will have four pipe connections, unless the equipment provides either heating only or cooling only. In this case, the equipment would have only two pipe connections.

Commissioning

HVAC (Heating, Ventilation and Airconditioning) component start-up procedures describe how to start the operation of each component. They specify the methods to be used and the checks that are needed. Start-ups and related measurements are carried out by the contractor. Commissioning provider assists the contractor in the beginning of each start-up process and reviews that no systematic errors are made.

Piping

– What is Primary-Secondary Pumping?
– PRIMARY-SECONDARY BASICS.
– PRIMARY-SECONDARY RULES, DEFINITIONS.
WHEN TWO PIPING CIRCUITS ARE INTER-CONNECTED, FLOW IN ONE WILL CAUSE FLOW IN THE OTHER, T0 A DEGREE DEPENDING UPON THE PRESSURE DROP IN THE PIPING COMMON T0 BOTH.

Equipments, HVAC, Piping

Expansion tanks are a necessary part of all closed hydronic systems to control both minimum and maximum pressure throughout the system. A comprehensive review of tank types and sizing procedure for expansion tanks.

Equipments, HVAC, Piping

How does Boyle’s law relate to sizing expansion tanks in domestic hot water systems?
what size expansion tank is required?

HVAC

The heating, ventilation, and air conditioning (HVAC) equations. In both U.S. and Metric units.

Equipments, Piping

Pump sizing involves matching the flow and pressure rating of a pump with the flowrate and pressure required for the process. The mass flowrate of the system is established on the process flow diagram by the mass balance. Achieving this mass flowrate requires a pump that can generate a pressure high enough to overcome the hydraulic resistance of the system of pipes, valves, and so on that the liquid must travel through. This hydraulic resistance is known as the system head.

HVAC, Refrigeration

Although work is underway to develop alternative refrigerants and improve refrigerant management strategies, the phase-down of HFCs will impose constraints on vaporcompression equipment that will require trade-offs among cost, efficiency, and safety. These constraints could present market opportunities for alternative space-conditioning technologies. Alternative technologies based on their development status (some technologies are in very early stages of development), potential for energy savings, and other factors that may affect their ability to compete with vapor-compression systems.

HVAC

There are many different designs of chilled beams on the market, which makes the selection and comparison between product types and manufacturers difficult. However, there are technical details that can be compared when making a chilled beam selection.
There are four main steps that should be taken into account when selecting chilled beams

HVAC

There are a number of types of radiant chilled ceilings on the market. Ensuring good thermal conductivity between the cooling element and the other parts of the radiant chilled ceilings is important to ensure maximum performance. The cooling capacity of chilled ceilings is one of the major selection criteria.

General

The piping and radiator connections shown in this section are diagrammatic and illustrate the proper method of making piping connections in steam heating processes.
– Two pipe steam systems radiator connections
– Piping connections for unit heaters (steam)
– Two pipe– #steam trap installations
– Two Pipe Steam Systems Convector Connections
– Exposed #Pipe #Coils– Two Pipe Steam
– One pipe #steam systems radiator connections
– One pipe steam systems #convector connections
– One pipe steam systems convector connections

Equipments

There are many types of steam traps each having its unique characteristics and system benefits. Deciding which type of trap to use is sometimes confusing and, in many cases, more than one type can be used. The following is intended to point out system conditions that may be encountered and the characteristics of each type of trap.
Steam Trap – Operation, Advantages, Disadvantages And Primary Applications

Equipments

Hydropneumatic tanks are primarily used in a domestic water system for draw down purposes when the pressure booster system is off on no-flow shutdown (NFSD). The NFSD circuitry turns the lead pump off when there is no demand on the system. While the system is off in this condition, the hydropneumatic tank will satisfy small demands on the system. Without the tank, the booster would restart upon the slightest call for flow such as a single toilet being flushed or even a minute leak in the piping system.
Hydropneumatic tank sizing is dependent on two factors:
– Length of time you wish the pumps to remain off in a no-flow situation.
– The tank location in relation to the pressure booster.

Refrigeration

VRF systems are available either as heat pump systems or as heat recovery systems for those applications where simultaneous heating and cooling is required. In addition to providing superior comfort, VRF systems offer design flexibility, energy savings, and cost effective installation.
A VRF system offers flexible installation and energy-saving cooling and heating comfort and should be considered as an alternative to traditional systems for those applications where zoning or part load operation is required.

HVAC

The interrelationships among human beings, ambient conditions, and conditions within the built environment. Metabolic Rates For Typical Tasks

Equipments, Refrigeration

VRF systems utilize refrigerant as the working fluid and can provide cooling only to multiple indoor fan-coil units connected to a single condensing unit, either cooling or heating to multiple indoor fan-coil units connected to a single heat pump unit, or both cooling and heating simultaneously to multiple indoor fan-coil units connected to a single heat recovery unit.

HVAC

Thermal energy may be stored in three main ways:
– Sensible Storage
– Latent Storage
– Thermo-Chemical Storage.
In addition, the two common thermal storage strategies employed are:
– Load Levelling Strategy
– Load Shifting Strategy

HVAC

The process by which fresh air is introduced and contaminated air is removed from an occupied space is termed ventilation. Ventilation is necessary to provide a continuous supply of oxygen. Air changes per hour (ACH) is a measure of the air volume added to or removed from a space in one hour, divided by the volume of the space.

Variable Air Volume (VAV) Systems

Constant Air Volume (CAV) Systems

Cooling Towers (Capacity Control)

Cooling Towers (Free Cooling Operation)

Maintaining And Cleaning Stainless Steel

Commissioning, Equipments, HVAC, Piping

Carrier Revit Files

Refrigerant Ph Diagram (Part 2)

Pack Calculation Pro Software Download

Refrigeration, Softwares

Cooltools Software Download

Refrigeration, Softwares

Coolpack Software Download

Refrigeration, Softwares

Datacenter Liquid Cooling Methods

Equipments, HVAC, Piping, Refrigeration

Refrigerant Piping (Part1)

4-Pipe And 2-Pipe Heating And Cooling Plants

Commissioning, HVAC, Piping

Hvac Component Start Up

Primary Secondary Pumping

Expansion Tank Sizing Formulas

Equipments, HVAC, Piping

Expansion Tanks

Equipments, HVAC, Piping

Hvac Equations (U.S./Metric)

Pump Sizing Core Concepts

Equipments, Piping

Non Vapour Compression Cycles

HVAC, Refrigeration

Chilled Beam Selection

Radiant Chilled Ceiling Selection

Typical Piping For Steam Heating

Steam Trap Explained Totally

Hydropneumatic Tank Sizing

Variable Refrigerant Flow (VRF) Benefits

Metabolic Rates For Typical Tasks

Variable Refrigerant Flow Systems

Equipments, Refrigeration

Thermal Storage (HVAC)

Air Changes Per Hour