暖通空调变流量水系统中定压差技术的应用

随着人们对生活品质的要求和节能意识的不断提高以及空调系统的大型化，变流量水力系统在暖通空调工程中占据越来越重要的位置。变流量系统在运行过程中各分支环路的流量是随着外界环境负荷的变化而变化的，因此对系统的水力平衡和调节提出了很高的要求。目前为了解决暖通空调变流量水力系统的动态水力平衡和调节问题，定压差技术得到了广泛的应用，     

动态压差平衡阀与电动调节阀组合与一体式动态平衡电动调节阀的性能比较

随着人们生活水平和节能意识的不断提高，变流量系统在暖通空调工程中占据越来越重要的位置，同时，一种新型的水力系统——全面平衡的变流量水力系统也在暖通空调工程中得到越来越广泛的应用。     

暖通空调变流量水力系统的全面平衡

分析了暖通空调工程定流量和变流量系统水力平衡的特点,提出了变流量系统全面平衡的概念,结合工程实例分析了全面平衡变流量水力系统的舒适性和节能性。     

暖通空调变流量全面水力平衡系统常用形式介绍

介绍了暖通空调系统常用的几种水力平衡设备，并对常见的几种变流量全面水力平衡系统进行了分析。     

变流量系统动态水力平衡设备 能否取代静态水力平衡阀

随着人们生活品质要求、节能意识的不断提高以及空调系统的大型化，变流量水力系统在暖通空调工程中占据越来越重要的位置。变流量系统由于各末端设备的水流量是随着外界环境负荷的变化而变化的，因此对空调水系统的控制和水力平衡提出了很高的要求。最早为解决水力平衡问题使用的主要是静态水力平衡阀，但是随着全面水力平衡技术的广泛应用，     

暖通空调变流量全面水力平衡系统如何进行冬夏转换

随着人们生活品质要求、节能意识的不断提高以及空调系统的大型化，变流量水力系统在暖通空调工程中占据越来越重要的位置。变流量系统在运行过程中各分支环路的流量是随着外界环境负荷的变化而变化的，因此对系统的水力平衡和调节提出了很高的要求。目前在越来越多的暖通空调工程中采用了全面水力平衡技术，通过采用具有静态或动态水力平衡功能的设备来满足系统的水力平衡和调节要求，目前常用的具有动态水力平衡与调节功能的设备主要有用于风机盘管的动态平衡电动开关阀和用于空调箱、空气处理机组等处的动态平衡电动调节阀或动态压差平衡阀与电动调节阀组合。     

动态流量平衡阀和电动调节阀组合能代替动态平衡电动调节阀么？

随着人们生活水平和节能意识的不断提高，变流量系统在暖通空调工程中占据越来越重要的位置，同时，一种新型的水力系统——全面平衡的水力系统也在暖通空调工程中得到越来越广泛的应用。     

暖通空调水力平衡分析

本文介绍了暖通空调系统中水力失调与水力平衡的概念及其分类，并对其定流量系统及变流量系统水力失调的特点进行了分析，提出了实现水力平衡的措施并介绍了典型的几种系统形式。     

暖通空调变流量系统几种平衡调节方案的选择

在暖通空调变流量水力系统中,水力平衡及调节方案的选择是个重要的课题.合理地选择水力平衡及调节方案,可以满足暖通空调系统的舒适节能性要求,使系统高效、稳定同时经济地运行.     

暖通空调水力平衡分析

本文介绍了暖通空调系统中水力失调与水力平衡的概念及其分类,并对其定流量系统及变流量系统水力失调的特点进行了分析,提出了实现水力平衡的措施并介绍了典型的几种系统形式。     

动态流量平衡阀的原理及其应用

分析了采暖和空调系统中的水力工况及存在问题,提出了解决水力失调的方法;介绍了动态流量平衡阀在暖通空调水系统中的应用及其经济效益,并提出了在系统设计时应注意的问题。     

压差电动调节阀的节能控制分析

本文分析空调变流量水系统调节过程中存在的问题,通过对空调水系统采用节能控制技术后达到的运行效果,分析节能控制技术在空调领域应用所具有的舒适性和节能性。     

变流量系统全面水力平衡的核心——关键点定压差技术

介绍了变流量水系统中流量调节的几种形式及定压差技术的工作原理和作用,分析了关键点定压差技术可用于变流量水系统实现全面水力平衡的原因,结合实际工程介绍了关键点定压差技术的几种应用形式。     

变流量水系统中水力平衡问题的探讨

分别从静态水力平衡、动态水力平衡角度分析了静态水力平衡阀、自力式流量控制阀、自力式压差控制阀与电动调节阀组合使用的特性,认为自力式流量控制阀与电动调节阀组合不适合应用在变流量水系统中.     

平衡阀在空调水系统中的应用分析

针对水力失调的成因及解决方法进行了探讨,并分析了静态平衡阀和动态平衡阀在空调水系统中的设置形式和选取原则,给出了较为可行的处理方案,以确保暖通空调系统的正常运行。     

空调系统节能改造技术措施分析

本文探讨了空调系统节能改造中具有较好投资回报期的措施,包括风机盘管改造与控制、过渡季节空调箱利用新风供冷、空调系统区域控制、冷冻水变水量控制以及制冷主机改造。     

Predictions of energy savings in HVAC systems by lumped models

An approach to optimizing the energy efficiency of a Heating, Ventilating, and Air Conditioning (HVAC) system is presented that utilizes computational predictions of the effect of heat load distribution on moist air temperature, density, and humidity variation. Lumped-HVAC (L-HVAC) is a new lumped parameter code that couples fluid transport, energy transport, thermodynamics, and psychrometrics in an HVAC system. This code contains a nonlinear implicit solution algorithm for steady-state and transient calculations for flow resistance, water mass balance, and energy conservation. L-HVAC has been validated using a simplified analytical model, the commercial lumped parameter code SINDA/FLUINT, and experimental measurements. Steady-state calculations for a single-room system suggest an order of magnitude greater energy savings using a variable chiller power control approach compared to control damper and variable-drive fan approaches. L-HVAC was also applied to predict that the fraction of latent to total heat load influences the steady-state system temperature by up to 0.4 °C for the example system in this study.     

Analysis of local optima in predictive control for energy efficient buildings

We study the problem of heating, ventilation and air conditioning (HVAC) control in a typical commercial building. We propose a model predictive control (MPC) approach which minimizes energy cost while satisfying occupant comfort and control actuator constraints, using a simplified system model and incorporating predictions of future weather and occupancy inputs. In simplified physics-based models of HVAC systems, the product between air temperatures and flow rates arising from energy balance equations leads to a non-convex MPC problem. Fast computational techniques for solving non-convex optimization can only provide certificates of local optimality. Local optima can potentially cause MPC to have worse performance than existing control implementations, so deserve careful consideration. The objective of this article is to investigate the phenomenon of local optima in the MPC optimization problem for a simple HVAC system model. In the first part of the article, simplified physics-based models and MPC design for two common HVAC configurations are introduced. In the second part, simulation results exhibiting local optima for both configurations are presented. We perform a detailed analysis on the different types of local optima and their physical interpretation. We then use this analysis to derive physics-based rules to exclude classes of locally optimal control sequences under specific conditions.     

Development and validation of online models with parameter estimation for a building zone with VAV system

The energy consumption by building heating, ventilating, and air conditioning (HVAC) systems has evoked increasing attention to promote energy efficient control and operation of HVAC systems. Application of advanced control and operation strategies requires robust online system models. In this study, online models with parameter estimation for a building zone with a variable air volume system, which is one of the most common HVAC systems, are developed and validated using experimental data. Building zone temperature and zone entering air flow are modeled based on physical rules and only the measurements that are commonly available in a commercial building are used. Various validation experiments were performed using a real-building test facility to examine the prediction accuracies for system outputs. Using the online system models with parameter estimation, the prediction errors for all validation experiments are less than 0.28 °C for temperature outputs, and less than 84.9 m³/h for air flow outputs. The online models can be further used for local and supervisory control, as well as fault detection applications.     

自动喷水灭火系统管网的水力模型分析

采用有限元法分析了自喷系统管网的水力平衡数学模型，集合各个管段水力平衡的单元矩阵方程为管网水力平衡的整体矩阵方程，通过引入节点水压边界条件并求解整体矩阵方程，自动配管，迭代计算喷头的流量，得出管网水力工况。给出了编程算法步骤，经实例运算，可快捷准确地完成水力平衡计算。