中美两国“容积式CO2制冷压缩机（组）”标准的对比

介绍中美两国制冷空调行业协会在容积式CO2制冷压缩机(组)标准化合作方面的进展。对中国国家标准GB/T29030—2012《容积式CO2制冷压缩机(组)》和美国AHRI 571:2012标准《容积式CO2制冷压缩机(组)性能评定》进行分析,主要从适用范围、试验工况、测试方法、试验参数及性能允差、计算参数、油循环率等方面对两国标准进行详细的对比。该分析研究有助于推进容积式CO2制冷压缩机(组)标准的国际化进程。     

远置式陈列柜制冷电能消耗理论分析

基于远置式陈列柜能效标准和冷藏陈列柜标准,以半封闭压缩机性能参数表进行计算,分析工质、压缩机容积、蒸发温度、频率等参数对远置式陈列柜制冷电能消耗的影响。结果发现R134a计算值偏离实验值程度最小;小压缩机并联比使用大压缩机能获得更低的制冷电能消耗偏离系数;较高的蒸发温度,可以使得实际制冷电能消耗减少,但是相应的会导致计算值偏离实际值的程度增加;压缩机频率较低可以使得计算偏离系数较小。     

滑板补气滚动转子式压缩机性能试验研究

针对采用常规滚动转子式压缩机的空气源热泵系统冬季制热量不足,在极限制冷、制热工况下制热与制冷性能较差的问题,研发带有滑板补气结构的滚动转子式压缩机并对其进行测试。结果表明:与相同气缸容积的单级压缩机相比,在蒸发温度为-10℃,冷凝温度为45℃和过冷度为5℃的条件下,滑板补气滚动转子式压缩机的制热量提升12.4%,制热COP提升2%,制冷量提升13%,制冷EER提升1.3%。     

氨活塞式双级制冷压缩机运行特性数学模型

本文根据生产厂家提供的氨活塞式制冷压缩机在标准工况下运行特性参数，应用微机推导计算出各种氨双级制冷压缩机在实际运行工况下，制冷量随蒸发温度和冷凝温度变化的关系数据，绘制成一系列产品性能特性曲线图。在保证数值计算精度的前提下，采用最小二乘法多变量数据拟合出各种氨活塞式双级制冷压缩机运行特性数学模型。     

双级补气滚动转子式压缩机容积比的理论分析与试验研究

容积比是影响双级补气滚动转子式压缩机性能的关键参数。本文建立基于两级节流中间不完全冷却蒸气压缩式制冷循环的最佳容积比数学计算模型,并进行最佳容积比数学模型的试验验证,结果表明二者基本吻合。最后通过理论计算得到热泵式空调器在环境温度-35～54℃宽范围工况下的最佳容积比随工况变化的规律。     

氨活塞式单级制冷压缩机运行特性数学模型

本文根据生产厂家提供的氨活塞式制冷压缩机在标准工况下的运行特性参数，应用微机推导计算出各种氨单级制冷压缩机在实际运行工况下，制冷量蒸发温度和冷凝温度变化的关系数据，绘制成一系列产品性能特性曲线图。在保证数值计算精度下的前提下，采用最小二乘法多变量数据氦合出各种氨活塞式单级制冷压缩机运行特性数学模型。     

GREATLAB仿真软件在风管送风式空调制冷系统中的设计应用

用GREATLAB仿真软件对1.5HP风管送风式空调制冷系统压缩机、冷凝器、蒸发器、节流毛细管四个主要部件进行仿真模拟设计,代入到整个制冷系统的动态仿真模块进行仿真计算得出名义制冷工况下空调机组制冷量、功率、吸气温度、排气温度、吸气压力、排气压力等参数,并进行实验验证,得出名义工况下制冷量与仿真计算制冷量误差在5%以内。结果表明:GREATLAB仿真软件能够用于指导商用一拖一空调系统的设计,可作为开发和优化商用空调系统的有效工具。     

单螺杆压缩机内容积比优化对部分负荷性能提升的研究

螺杆式冷水机组全年大部分时间运行在部分负荷,提升部分负荷运行时压缩机的能效比,可有效降低机组全年运行能耗。现有的定频单螺杆式制冷压缩机,内容积比通常以100%负荷的运行工况设计。而部分负荷运行时,由于环境温度降低,机组冷凝温度低于100%负荷工况,压缩机排气压力与吸气压力比值下降。此时压缩机内容积比与压比不匹配,存在过压缩损失。针对部分负荷工况优化压缩机内容积比设计,可有效提高压缩机综合部分负荷能效比(IPLV),实现机组运行全年节能减排。     

数码涡旋管道机制冷变风量运行的实验研究

对采用数码涡旋压缩机的风管送风式空调(热泵)机组在标称制冷工况下的变风量运行进行了实验研究,得出了机组制冷能力、功耗、机组效率、出风温度、排气压力、排气温度、吸气压力等参数随风量变化的关系,分析了采用数码涡旋压缩机的管道机变风量运行的特点,为风管送风式空调(热泵)机组的节能、稳定运行提供了有价值的实验支撑。     

可变内容积比螺杆式压缩机的性能分析

随着冷水机组、单元式空调机和水源热泵机组等产品的能效指标从名义工况EER或COP发展到IPLV或ICOP,机组的变容量或变工况性能主要取决于压缩机的变容量或变工况性能。固定内容积比的螺杆式压缩机如果在偏离设计工况下工作,效率下降,进而导致整个机组的性能下降。本文研究变内容积比螺杆式压缩机,内容积比可变化,使得压缩机内压比与外压比与工况相适应,可提升压缩机效率及机组性能。应用于冷水机组、水源热泵机组时,水源热泵机组在制冷工况时能效比可提高14.1%～35%,冷水机组的IPLV可提高7.2%左右。     

行业标准JB/T《高温热泵用全封闭涡旋式制冷剂压缩机》要点解读

高温热泵技术可实现在工商业诸多领域的推广应用,其核心设备压缩机产品的标准化意义重大。本文阐述已完成报批的行业标准JB/T《高温热泵用全封闭涡旋式制冷剂压缩机》的编制背景,从标准名称、适用范围、基本参数、名义工况与性能允差、其他综合性能评价项目等方面解读该标准的技术要点。     

压缩机表面产生凝露的原因及其解决措施

变频多联机中距离室内机近的压缩机表面在运行中出现凝露现象,并伴随压缩机内油翻泡,油面下降。从理论方面分析该现象：在名义制冷、最大制冷工况下,制冷剂循环量没有控制好,导致过多的制冷剂进入压缩机后继续蒸发,温度降低到露点温度以下,从而出现压缩机表面凝露。为此,提出相应的控制措施,较好地解决了该问题,对保证多联机系统的稳定安全可靠运行具有一定的指导意义。     

Development of a virtual variable-speed compressor power sensor for variable refrigerant flow air conditioning system

This paper proposed a universal virtual variable-speed compressor power (VVCP) sensor for VRF system based on 20-coefficient model. Compressor power can be obtained by the VVCP sensor using three input parameters (frequency, condensing temperature and evaporation temperature) which are measured by system itself. The performance of the proposed VVCP sensor is evaluated using experiments data. Experimental conditions include cooling, heating and non-standard refrigerant charge levels. The result shows that the mean square percentage errors (MSPE) are 9.9% under cooling conditions and 7.96% under heating conditions. The MSPE are 9.88% at steady state and 9.75% at dynamic state when the VVCP sensor is applied under nine different refrigerant charge levels. It demonstrated that the proposed VVCP sensor can obtain compressor power under cooling, heating and non-standard refrigerant charge levels, which could be applied to do operational monitoring and fault detection and diagnosis for VRF system at low cost.     

Modeling evaluation of a direct-expansion solar-assisted heat pump water heater using R410A

A direct-expansion solar-assisted heat pump (DX-SAHP) system by using R410A as refrigerant is described, which can supply domestic hot water during the whole year. Based on the distributed parameter and homogeneous flow models of collector/evaporator and condenser, the lumped parameter models of compressor and electronic expansion valve, and the refrigerant charge model, a numerical model is developed to estimate the thermal performance of the system. Given the structure parameters, meteorological parameters, initial and final water temperatures, for a fixed superheat degree, the effects of the refrigerant charge quantity on the performance parameters of the system are analyzed, such as compressor power, heat gain of collector, heating time, collector efficiency and system COP. Furthermore, for a fixed refrigerant charge quantity, the effects of various parameters, including solar radiation, ambient temperature, compressor speed and initial water temperature, have been simulated and analyzed on the thermal performance of the system.     

Modeling of rotary vane compressor applying artificial neural network

The thermal modeling of rotary vane compressor (RVC) was performed in this paper by applying Artificial Neural Network (ANN) method. In the first step, appropriate tests were designed and experimental data were collected during steady state operating condition of RVC in the experimental setup. Then parameters including refrigerant suction temperature and pressure, compressor rotating speed as well as refrigerant discharge pressure were adjusted.With these input values, the operating output parameters such as refrigerant mass flow rate and refrigerant discharge temperature were measured. In the second step, the experimental results were used to train ANN model for predicting RVC operating parameters such as refrigerant mass flow rate and compressor power consumption. These predicted operating parameters by ANN model agreed well with the experimental values with correlation coefficient in the range of 0.962-0.998, mean relative errors in the range of 2.79-7.36% as well as root mean square error (RMSE) 10.59 kg h⁻¹ and 12 K for refrigerant mass flow rate and refrigerant discharge temperature, respectively. Results showed closer predictions with experimental results for ANN model in comparison with nolinear regression model.     

Development and evaluation of virtual refrigerant mass flow sensors for fault detection and diagnostics

Refrigerant mass flow rate is an important measurement for monitoring equipment performance and enabling fault detection and diagnostics. This paper presents and evaluates three different virtual refrigerant mass flow (VRMF) sensors that use mathematical models to estimate flow rate using low cost measurements. The first model uses a compressor map that relates refrigerant flow rate to measurements of condensing and evaporating saturation temperature, and to compressor inlet temperature measurements. The second model uses an energy-balance method on the compressor that uses the compressor power consumption. The third model is developed using an empirical correlation for an electronic expansion valve (EEV) based on an orifice equation. The three VRMFs are shown to work well in estimating refrigerant mass flow rate for various systems under fault-free conditions with less than 5% RMS error. The combination of the three VRMFs can be utilized to detect and diagnose when the compressor and/or expansion device is not providing the expected flow.     

Experimental investigation on convective heat transfer mechanism in a scroll compressor

This paper describes an experimental study on the convective heat transfer inside the scroll compressor. An experimental refrigeration system is composed with extensive instrumentations in the compressor that is operated at variable speeds. The 13 thermocouples installed inside the compressor monitor the temperatures of the scroll wrap during compression process of refrigerant. The temperature and the pressure of refrigerant at suction, and the pressure at discharge ports are measured, and applied to the numerical simulation as the operating condition parameters. The temperature measured at the discharge port is used to verify the simulation result with relevant heat transfer coefficient. This paper describes the effect of motion of the orbiting scroll on the convective heat transfer in the scroll wraps. Separate experiments are performed to investigate the heat transfer in such a peculiar physical condition. With this experimental result, the effect of the oscillation of the wall on the heat transfer is quantitatively analyzed and applied to the simulation of compression process in scroll compressor. The whole consecutive compression processes in the scroll compressor is simulated in detail by solving equations of mass and energy balance for the refrigerant. The modified heat transfer coefficient correlation considering the effect of motion of the orbiting scroll predicts the discharge temperature better than other typical heat transfer coefficients.     

地埋管换热器变热流工况下换热模型及其试验验证

在制冷空调产品及热泵热水机国家标准规定的名义工况下,比较CO2跨临界循环与R22,R410A和R404A单级蒸气压缩循环的理论循环效率。结果表明：在空调制冷名义工况下,R22理论循环效率最高,CO2的理论循环效率只有R22的50％～60％;在热泵热水机名义工况下,CO2的理论循环效率最高,可以达到R22的145％;CO2跨临界循环受冷却器压力及出口温度2个方面的影响,适当降低CO2冷却器出口温度可改善循环效率,应用CO2制冷剂需要通过改善循环和优化控制提高系统的能效。