基于k-means聚类的地源热泵机组运行策略优化研究

以上海某地源热泵为研究对象,基于长期实测数据对全年工况性能特性进行了研究。通过k-means对全年工况的日逐时负荷进行聚类分析,获得采暖、制冷和过渡季节等不同季节最佳族数及对应族下典型日负荷曲线特性。构建地源机组的性能仿真模型,通过实测数据获得模型相关参数值。分别以最优制热制冷性能系数为目标,建立了运行负荷配比优化模型,并将模型应用于上述不同季节典型工况,对各典型工况下的运行策略进行优化,获得各工况下最优运行策略。通过与实测数据的对比,运行策略优化有效提高了热泵系统的能效。     

变频多联机的一般控制规律及典型控制系统故障分析

本文主要从变频多联机控制系统的典型故障、变频多联机空调制冷工况下的基本控制、多联机空调制热工况下的基本控制与多联机空调基本保护控制四方面,进行了分析,以供借鉴。     

多联机空调系统在线能耗测量方法研究

实时运行能耗是实现多联机节能运行和智能控制的基础数据，但因成本原因，实际运行的多联机空调系统很少安装功率表对其能耗进行实时监测，因此研发低成本且具有工程精度的实时能耗测量方法对于多联机的节能降碳具有重要意义。本文提出了适用于单片机运行的频率-电流曲面拟合法和适用于云端大数据运算的神经网络自学习法，实验结果表明，2种在线能耗测量算法均具有良好的测量精度，在名义制冷、名义制热、最大制冷、低温制热和除霜等工况及在各种工况下自由切换连续45 h运行时，对多联机系统总功率的测量误差均在±5%以内。     

喷气增焓技术对多联机制冷性能影响分析

为了使多联式空调机组在制冷工况时制冷性能更佳,本文在机组开启喷气的情况下,名义制冷全开负荷占比98.13%,制冷能力比普通多联机高13.46%。高温制冷工况下,全开负荷开喷气能力占比89.1%,比常规多联机提升13.17%。制冷能力可提升10%～15%。开喷气的情况下,系统过冷度比不开喷气高3～5℃,可降低室内侧噪音,提高用户使用效果。     

大容量多联机空调系统的运行特性分析

利用多联机空调(MSAC)系统仿真平台,以制冷工况下室内机容量连续调节的多联机空调系统为例,探讨了大容量多联机系统的稳态运行特性。结果表明,多联机空调系统随连接管长度的增加,其制冷量有较大的衰减,且制冷能效比COPc的性能域宽度逐渐增大;对于单模块室外机组多联机空调系统而言,采用多台压缩机时,其部分负荷下的COPc优于单台压缩机构成的系统;由多个模块室外机组并联拼装构成的多联机空调系统,随室外机组数量的增加,其COPc逐渐降低,故并联的模块室外机组数量不宜太多,以免削弱多联机系统部分负荷率时的高能效比优势。     

多联机室内机不同送风形式对室内环境的影响

本研究基于清华大学STECH3模拟计算软件,构造了不同形式多联机室内机用于同一典型办公室内的计算模型。计算了制冷和制热工况下,不同形式的多联机室内机送风形式对于室内温度场和风速的影响,并对计算结果进行了对比,得出了一些客观的结论和观点,希望为多联机的产品开发和合理使用提供有益的参考。     

基于Dymola的燃气热泵系统制冷工况仿真研究

采用面向对象的、多领域的物理系统建模语言Modelica和Dymola编译器编制了燃气热泵各部件的仿真程序,包括天然气发动机、压缩机、蒸发器、冷凝器、膨胀阀等。利用该模型对样本燃气热泵机组制冷工况进行了调试,并将机组调试模型与样本数据进行了对比,验证了模型的可靠性;在额定测试条件下,机组模型50%~100%负荷工况的运行性能很好地还原了样本数据;同时还考察了室外环境温度变化对机组性能的影响。     

多联机空调系统的性能域

给出了建筑物室内负荷分布特征的描述方法.以制冷工况下室内机容量连续调节的多联机为对象,模拟研究了室内负荷分布不均匀性对多联机系统部分负荷特性的影响规律.指出在室内外环境参数不变的条件下,多联机空调系统在部分负荷下的COP存在一个由负荷率和负荷不均匀性指数决定的"性能域",并分析了影响性能域形状的因素.     

一种冷水机组季节性能评价新指标与多台机组联合运行性能评价

综合部分负荷性能系数IPLV是评价冷水机组季节运行性能的重要指标,但在对其合理性的评价上存在诸多争议。从季节性能评价指标的物理本质出发,构建了描述单台冷水机组性能的季节部分负荷性能系数SPLV指标;基于SPLV的评价思想,提出了描述多台冷水机组联合运行时的季节部分负荷性能系数SPLV(N)的计算方法和测试工况,并应用SPLV(N)对不同类型冷水机组进行了性能评价。结果表明,所构建的SPLV指标可以更为真实地反映冷水机组的季节运行性能;SPLV(N)的大小与冷水机组的性能曲线形状有很大关系,不同类型的机组各有其适宜的应用形式。     

北京京林大厦中央空调系统设计

北京京林大厦是集商务、住宿、娱乐为一体的综合性建筑,空调系统采用水冷数码变容量多联水环热泵系统,在冬夏季节,空调系统与生活用中央热水系统互为利用,在满足供热制冷需求的基础上减少能源消耗;在春秋过渡季节,空调系统完全处于内部热量平衡状态,运行效率大大提高,降低运行费用。水冷数码变容量多联机是技术创新的多联机,它既继承传统水源热泵系统特点,又秉承风冷多联系统的优势,机组综合性能系数IPLV高达5.2,有效降低空调系统运行费用。     

数据中心冷热电联供系统全工况热力性能分析

建立了夏热冬冷地区某数据中心天然气冷热电联供系统全工况数学模型。得到了燃气轮机和双效溴化锂机组的全工况性能规律,计算了系统夏季典型日冷热电输出及一次能源利用率、相对节能率,并比较了设备容量配置对系统性能的影响。结果表明,数据中心总冷负荷相对常规建筑较大,联供系统夏季典型日的热力性能总体较高。在研究范围内,增大溴冷机组容量或减小电制冷机组容量,有利于提高系统的总体一次能源利用率和相对节能率。本研究为数据中心冷热电联供系统的设计和运行优化提供依据。     

Establishment and validation of modified star-type RC-network model for concrete core cooling slab

Thermal properties of concrete core cooling slab have direct and strong influence on its dynamic cooling performance. Star-type RC-network model can be used to simulate thermal dynamic performance of concrete cooling slab, but the heat resistance and the heat capacity of assumed core temperature layer in the model is difficult to determine. This article proposed a method to define these two thermal properties in geometric way, and modified RC-network model was established in order to validate the method. Then thermal steady and dynamic performances of two typical concrete core cooling slabs were simulated by the modified star-type RC-network model and FEM respectively. The results indicate that the modified RC-network model was in good agreement with FEM both in dynamic and steady cooling performance simulation. Furthermore, application scope of the modified RC-network model was investigated and defined.     

Experimental study on hysteretic performance of steel-plate assembled buckling-restrained brace

提出一种钢板装配式屈曲约束支撑,支撑的各部件由钢板装配而成,在一字形核心单元局部进行了开孔,以实现定点屈服和多点屈服耗能,外约束单元端部采取了局部加强措施,以避免端部局部失稳破坏。设计、制作了3个试件,对其进行低周反复加载试验,研究核心单元开孔、支撑端部构造以及支撑固接和铰接连接形式对屈曲约束支撑滞回性能的影响。研究结果表明：该种支撑的滞回曲线饱满,耗能性能稳定,等效黏滞阻尼比在0.37~0.48之间;支撑延性好,累计塑性变形能力强;在设计位移下支撑拉压不均匀系数能够满足规范要求;支撑恢复力模型可采用双线性模型模拟;核心单元开孔可实现定点屈服和多点屈服耗能;支撑端部的加强措施对端部起到了保护作用;端部无论采用固接还是铰接都可以保证支撑的工作性能。     

Part load performance of air-cooled centrifugal chillers with variable speed condenser fan control

Air-cooled centrifugal chillers are commonly used in commercial buildings but their performance analysis is lacking. This paper investigates the part load performance of the chillers via a thermodynamic model. The model was validated using a wide range of operating data from an existing chiller with specific settings of outdoor temperature and condensing pressure in controlling the condensing temperature. The validated model was developed specifically to ascertain the maximum coefficient of performance of chiller (COP) together with the strategy for optimizing the condensing temperature under various operating conditions. It is found that the highest COP occurs at a part load ratio (PLR) of 0.71–0.84, depending on the outdoor temperature and the control of condensing temperature, rather than at full load. Yet the chillers operating at such part load conditions will cause extra energy used for the early staging of chilled water pumps. To minimize the overall chiller plant energy consumption, it is still preferable to implement chiller sequencing based on the full load condition than on the aforementioned PLRs. The results of this paper present criteria for implementing low-energy strategies for operating air-cooled chillers satisfying a given building cooling load profile.     

大型地下工程用除湿型水环热泵机组研制

提出了一种新型除湿水环热泵机组,能除湿、准确控温和制热,可满足地下工程部分负荷和满负荷的不同需求,并通过水环实现工程内热量转移.通过PLC控制压缩机荷载和制冷剂三通比例调节,消除了调温盲区,送风的温湿度精度提高;通过双流向设计,热泵工况时增加冷凝面积等技术,机组运行性能得到显著提高.在测试平台上对机组性能进行了测试.     

间接式污水源热泵机组节能技术分析

分析了间接式污水源热泵机组节能技术,包括提高压缩机效率,改善压缩机工作条件,减小传热温差,引射回油/液等。理论计算结果表明,与普通污水源热泵机组相比,间接式污水源热泵机组夏季制冷工况下性能系数可提高20%左右,冬季制热工况下性能系数可提高17%左右。     

Façades and summer performance of buildings

External cooling loads of a building façade are caused mainly by shortwave irradiance transmission, but also secondary heat flows from the internal glass panes and through ventilation gains from the façade. In a double façade with sun-blinds in the air gap, thermal energy is produced through absorption on the blinds. The work quantifies the thermal performance of single and double façades under summer conditions using laboratory and full scale building experiments. The experimental results were used for model validation and parameter studies were done using dynamic building simulation tools.     

An experimental study of energy consumption and thermal comfort for electric and hydronic reheats

This paper compares the performances of electric and hydronic reheat modes for variable-air-volume units using experimental data for a building. The comparisons are made based on the daily energy consumption associated with each reheat mode and comfort performances within a building zone. Data are collected from a full-scale heating, ventilating, and air conditioning system. Weather conditions are considered and the corresponding energy distributions are evaluated. The results showed that the energy for the air handling unit using hydronic reheat is lower than that using electric reheat by about 24% when the air handling unit is operated in either the mechanical or mechanical and economizer cooling mode and 33% for the economizer cooling mode. The reheat energy for the variable-air-volume units using hydronic reheat is lower by about 75% than for electric reheat for either the mechanical or mechanical and economizer cooling mode and 54% for the economizer cooling mode. The main reason for the low-energy consumption using hydronic reheat is attributed to the lower requirement for the minimum air flow across the reheat coil. Electric reheat provides a slightly cooler comfort environment than that for hydronic reheat.     

Reversible heat pump model for seasonal performance optimization

Building is one of the economical sectors where solutions are available to significantly reduce energy consumption and greenhouse gases emissions. Electric heat pumps are one of the solutions favored in Europe. Europe recently adopted a conventional primary energy to electricity ratio which enables to compare electric heat pumps and fossil fuel boilers. This leads to an increased consideration for the evaluation of the seasonal performances of heat pumps.Nowadays, the design and sizing of heat pumps are still based on full load performance in order to fulfill thermal comfort under extreme conditions. However, the HVAC industry is switching to designs based on improved seasonal performance. The objective of this work is to model an air to water reversible heat pump that can re-design its components for seasonal performance improvement.In this context, we will present a system model including detailed sub-models of each component of the system: heat exchangers, compressor, and expansion valve. The model converges with the system thermodynamic equilibrium after simulating each component separately. Results obtained are validated through experimental data per component and for the whole cycle. Modeling requirements for the purpose of simulating seasonal performance improvements are discussed.     

微表处混合料性能及其应用

分析了微表处混合料配合比设计参数对混合料性能的影响,并通过湿轮磨耗试验和负荷车轮粘附砂试验对微表处混合料的性能指标进行了阐述,并论述了其在工程应用中应注意的问题,以推广微表处混合料的应用。