Engineering & Knowledge - HVAC-R & Solar Engineering Resource

基础与工程

Pump Construction (Part1)

In 1689 the physicist Denis Papin invented the centrifugal pump and today this kind of pump is the most used around the world. The centrifugal pump is built on a simple principle: Liquid is led to the impeller hub and by means of the centrifugal force it is flung towards the periphery of the impellers. The construction is fairly inexpensive, robust and simple and its high speed makes it possible to connect the pump directly to an asynchronous motor.

Expansion Valves Selection

The expansion valve regulates the amount of compressed liquid refrigerant moving into the evaporator. It removes pressure from the liquid refrigerant to allow expansion or change of state from a liquid to a gas in the evaporator. In order to properly select Expansion Valves one should pay attention to the items that we mention in this post.

What Is Corrosion?

Corrosion is usually referred to as the degradation of the metal by chemical or electrochemical reaction with its environment, see figure 1. When considered broadly, corrosion may be looked upon as the tendency of the metal to revert to its natural state similar to the oxide from which it was originally melted. Only precious metals, such as gold and platinum are found in nature in their metallic state. – Types of corrosion – Uniform corrosion – Pitting corrosion – Crevice corrosion – Intergranular corrosion – Selective corrosion – Erosion corrosion – Cavitation corrosion – Stress corrosion cracking (SCC) – Corrosion fatigue – Galvanic corrosion

Water Hammer (Part1)

Under unfavorable circumstances, damage due to water hammer may occur in pipelines measuring more than one hundred meters and conveying only several tenths of a liter per second. But even very short, unsupported pipelines in pumping stations can be damaged by resonant vibrations if they are not properly anchored. By contrast, the phenomenon is not very common in building services systems, e.g. in heating and drinking water supply pipelines, which typically are short in length and have a small cross-section.

Water Tube Versus Fire Tube Boilers

Water tube boilers and fire tube boilers are two different types of steam boilers that are commonly used in industrial and commercial applications. Both types of boilers use a system of tubes to generate steam, but they differ in the way that the tubes are arranged and the way that the hot gases from the burner pass through the tubes.

Capillary Tube Refrigeration

A refrigeration capillary tube is a small, narrow tube that is used in refrigeration systems to control the flow of refrigerant. It is typically made of copper or other highly conductive metal, and is used in conjunction with a compressor, evaporator, and condenser to transfer heat from one location to another. The capillary tube is placed between the evaporator and the compressor in the refrigeration system, and it acts as a metering device to control the flow of refrigerant.

Refrigeration Formulas and Calculations

These formulas are commonly used in the field of refrigeration and air conditioning to calculate various performance parameters of a refrigeration system such as compression work, compression power, coefficient of performance, net refrigeration effect, capacity, compressor displacement, heat of compression, volumetric efficiency, and compression ratio. These formulas are based on the thermodynamics principles and are generally used to evaluate the performance of the refrigeration system and to optimize its design.

The coefficient of velocity (Cv)

Cv, or coefficient of velocity, is a measure of the flow capacity of a valve. It represents the number of gallons per minute (GPM) of water at 60°F that will flow through a valve with a one-inch opening at a pressure drop of one pound per square inch (PSI). Cv can be calculated using various formulas, such as the one based on water at 60F and one that takes into account the specific gravity of the fluid. Cv is a theoretical value and it may vary depending on the actual conditions of the valve. When selecting a valve for a specific application, it is important to consider the Cv in relation to the flow rate and pressure drop requirements of the system, as well as other factors such as ease of maintenance, cost, and safety.

Pipe Insulation Guideline

Pipe insulation is crucial for maintaining energy efficiency, temperature control, condensation control, noise reduction, and safety. ASHRAE provides specific thickness recommendations for different pipe sizes and temperature ranges in its standard 90.1. When selecting pipe insulation based on ASHRAE standards, it’s important to consider the temperature, pipe size, environmental considerations, fire resistance, and energy efficiency.

Refrigerant Piping – part2

In this post, we will be continuing our comprehensive training on how to size refrigerant piping. We will cover all the important aspects of this process, including determining the pipe size, pressure drop, and other factors. We will also discuss topics such as sizing refrigerant lines, equivalent length for refrigerant lines, and how to determine equivalent length. With this training, you will have the knowledge and confidence to size refrigerant piping accurately and correctly in any situation.

以前

标准与合规性

HVAC 管道设计：管道配件摩擦损失

使用开利标准的 HVAC 管道配件摩擦损失完整指南，涵盖损失系数、压降计算和高效空气分配设计的系统优化。

HVAC 管道设计：阻尼器、衰减器和线圈摩擦损失

使用 SMACNA 标准的 HVAC 阻尼器、衰减器和线圈摩擦损失完整指南，涵盖压降计算、组件选择和系统优化，以实现高效的空气分配设计。

HVAC 管道设计：圆形管道与矩形管道等效

使用 ASHRAE 标准的 HVAC 圆形管道与矩形管道等效的完整指南，涵盖转换公式、性能注意事项以及空间受限安装的系统优化。

HVAC 管道设计：管道摩擦损失

使用 ASHRAE 标准计算 HVAC 管道摩擦损失的完整指南，涵盖摩擦图表、压降分析和高效空气分配设计的系统优化。

HVAC 管道设计：管道压力分类

使用 SMACNA 标准进行 HVAC 管道压力分类的完整指南，涵盖安全高效管道系统的压力等级选择、施工要求和测试协议。

HVAC Duct Design – Sizing Contaminant-Extraction Ducts (Smoke | Grease | Gases | Dry & Moist Dust)

ASHRAE’s Pocket Guide lists minimum conveying velocities that keep contaminants airborne while they travel through exhaust ductwork. Table 2.9 (2013 edition, Ch. 02, pp. 60

HVAC 管道设计：商业厨房管道尺寸

使用 ASHRAE 和 NFPA 标准确定商业厨房管道尺寸的完整指南，涵盖排气罩设计、油脂管理、消防安全和食品服务运营的新风系统。

HVAC Duct Design: Duct Sizing by Velocity & Noise Criteria (NC)

使用符合 ASHRAE 和 CIBSE 标准的速度和噪声标准确定 HVAC 管道尺寸的完整指南，涵盖敏感应用的声学设计、速度限制和噪声控制。

HVAC 管道设计：通过等摩擦法确定管道尺寸

使用符合 SMACNA 和 ASHRAE 标准的等摩擦法确定 HVAC 管道尺寸的完整指南，涵盖计算程序、摩擦率选择和有效空气分配设计的系统优化。

HVAC 管道设计：管道尺寸 SMACNA 建议

使用 SMACNA 建议确定 HVAC 管道尺寸的完整指南，涵盖等摩擦、速度和静态回弹方法，以及有效空气分配的设计计算和系统优化。

数字工具和资源

Belimo SelectPro – 免费下载

免费下载 SelectPro 桌面应用程序。使用导出构建器、报价生成器和集中参考文档来调整和选择阀门、执行器和传感器。适用于 HVAC 工程师和承包商。

常见管道材料的热膨胀率

使用我们的交互式计算器轻松计算常见管道材料的热膨胀率。获取金属和塑料的准确数据、设计见解和可操作的表格，这对于关注系统可靠性和能源效率的 HVAC 工程师、设计师和顾问至关重要。

暖通空调设备预期寿命计算器

我们创建了专业的暖通空调设备预期寿命计算器。该应用程序提供了全面的计算，用于确定各种 HVAC 设备类型的剩余使用寿命。

适用于现代 HVAC 应用的 BIM 软件解决方案

As the HVAC industry continues to evolve in 2025, Building Information Modeling (BIM) has become an indispensable tool for professionals seeking to optimize design, installation, and maintenance processes. For HVAC engineers, contractors, and technicians, selecting the right BIM software can significantly impact project efficiency and outcomes. Let’s explore the most effective BIM solutions for HVAC applications.

McQuay软件下载

McQuay (As part of Daikin Industries) is one of the largest air conditioning, heating, ventilating and refrigeration companies in the HVAC/R industry. Therefore, we decided to make some softwares that this company has introduced to the industry based on their experience and knowledge available for download.

暖通空调职业机会

The HVAC/R (heating, ventilating, and air conditioning / refrigeration) industry is rapidly changing due to advancements in technology being spurred on by the need for increased energy efficiencies. Accordingly, the career opportunities open to an individual seeking employment in HVAC fields can be divided roughly into four categories, each dependent upon a different type or degree of education and/or training.

工程与知识