设备和系统
Variable Refrigerant Flow (VRF) Benefits
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.
水力发管箱尺寸
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.
Typical Piping For Steam Heating
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
制冷剂管道（第 1 部分）
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.
Datacenter Liquid Cooling Methods
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.
维护和清洁不锈钢
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.
Cooling Towers (Free Cooling Operation)
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.
Cooling Towers (Capacity Control)
免费的冷却系统可以为此类系统的所有者节省大量节省。但是，可用的势能节省数量几乎完全取决于整个系统设计以及用于系统使用的设备。通常，设计师必须平衡更高的设备成本和更大的节能机会。幸运的是，这些储蓄及其相关成本是合理量化的，因此设计师可以做出以可靠的信息为指导的明智选择。本文将描述免费冷却设计方案中的容量控制方法。
恒定空气体积（CAV）系统
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.
Variable Air Volume (VAV) Systems
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.
控件和自动化
HVAC Control Diagrams
In this blog post, we will introduce some of the most common HVAC control diagrams. We will also provide a brief explanation of each diagram and how its components work together. HVAC control diagrams are essential tools for designing, installing, and maintaining HVAC systems. They provide a visual representation of the system’s components, how they are interconnected, and how they are controlled. This information can be used to troubleshoot problems, optimize performance, and make informed decisions about system upgrades.