数据中心用气泵驱动热管复合空调节能潜力分析

针对数据中心用气泵驱动热管复合空调进行试验研究,结果表明:在中小型机房空调领域,采用变频转子式压缩机-气泵驱动热管复合空调AEER(北京)为5.56,可实现数据中心PUE1.30的目标;采用变频涡旋式压缩机-气泵驱动热管复合空调AEER(北京)为6.58,可实现数据中心PUE1.25的目标;在大型数据中心空调领域,利用磁悬浮压缩机-气泵驱动热管复合空调AEER(北京)为6.72,可实现数据中心PUE1.25的目标。气泵驱动热管复合空调技术配合间接蒸发冷却/凝等技术的运用,为现代数据中心节能减排提供了新的思路。     

自然冷却技术在机房空调中的应用现状

利用自然冷却技术是实现数据机房节能减排的重要途径,分析、调研现有自然冷却技术在机房空调领域运用情况,结果表明:新风或气-气热交换器技术适用性较差,难以满足机房空气品质以及机房空调可靠性要求;重力型分离式热管系统成本低,只适用于具有足够安装位置的场合;动力型分离式热管系统的推广受制冷剂泵价格的限制,它只适用于负荷较大(≥30 kW)的空调产品;变频多联技术为数据中心低成本、区域化、高效冷却提供新的解决方案,变频热管系统以及动力型热管背板系统成本低、适用性高,为研发数据中心冷却技术开辟新思路。     

数据中心用液泵驱动热管复合空调AEER和PUE分析

对数据中心用液泵驱动热管复合空调进行试验研究,结果表明:全变频液泵驱动热管复合空调可根据室外温度或室内负荷在同一个回路中切换运行模式,无控制死区;变频转子式压缩机-液泵驱动热管复合空调的AEER(北京)可达6.10,可实现PUE＜1.30的目标;变频涡旋式压缩机-液泵驱动热管复合空调的AEER(北京)可达9.19,可实...     

热管型机房空调系统设计与分析

针对数据机房、基站全天候空气调节需求,提出一种新型热管型机房空调系统,并设计制造额定制冷量为13 kW的热管型机房空调样机,在标准焓差实验室进行性能试验。结果表明:当室内外温差Δt≥13℃时,可利用室外自然冷源构造出具有节能效益的准热管,在满足13 kW制冷能力前提下,EER提高5%~35%;当Δt≥23℃时,系统运行热管模式,EER提高35%以上;在不增加成本的前提下,热管型机房空调全年能效比(AEER)较具有同等能力定速型、变频型机房空调分别高40%和20%以上;该技术为低成本节能型机房空调产品的开发开辟新思路。     

蒸发冷却式热管与蒸气压缩复合数据中心空调系统性能实验研究

为解决传统数据中心空调系统能耗高和冷却效率低等问题,本文提出了带有蒸发式冷凝器的制冷剂泵驱动热管与蒸气压缩复合数据中心空调系统,实验分析了不同室外温度与冷凝器风速下系统的运行性能.结果表明:在热管模式下,当室外温度低于0℃时,降低冷凝器风速能够提升系统COP;当室外温度高于0℃时,增大室外机风速能够提高系统节能性.降低...     

热管复合型机房空调研究与试验

针对数据机房、基站全天候温控需求,提出一种新型热管复合型机房空调系统,并设计出30 k W热管复合型机房空调样机,在标准焓差法实验室进行性能试验。结果表明:当室内外温差(Δt)达到28℃时,由制冷剂泵驱动的热管系统制冷量达到29.6 k W,能效比EER为7.9;当28℃Δt≥15℃时,系统运行复合模式,通过调节压缩机转速补偿热管系统制冷能力不足,实现按需制冷;制冷剂泵的驱动力克服了重力热管背板在水平方向上分液不均的问题,闪蒸气旁通技术解决了平行流蒸发器分液不均的问题;相较于传统压缩制冷系统,热管复合型机房空调系统成本低,全年能效比(AEER)提高50%以上。     

微通道型分离式热管基站节能特性实验研究

利用CFD技术对基站内的气流组织形式进行了优化,得出下进上出的气流组织形式可以提高冷风的利用率,同时开发了微通道型分离式热管基站,能保证发热机柜在设定温度范围内运行的要求,自动控制系统可以最优化的切换空调系统和微通道型分离式热管系统,保证机房内设备稳定运行。当室外环境平均温度为27℃时,制冷系统的COP可达6.23,具有较高的能效比。即使在夏季长时间的运行测试中,微通道型分离式热管基站空调压缩机的运行时间仅占基站总运行时间的39.1%,节电率达到44.7%,具有很好的节能降耗的效果。     

机械制冷/回路热管一体式机房空调系统研究

降低数据中心冷却系统能耗,已成为节能减排的迫切要求。热管自然冷却是降低这一能耗的有效方法之一。为解决热管自然冷却在炎热季节需要机械制冷辅助的问题,进一步提升热管自然冷却的节能潜力,本文提出一种新型机械制冷/回路热管一体式机房空调系统。利用三介质换热器将机械制冷回路和回路热管耦合起来,实现了二者的同时或单独工作,避免了现有系统依赖电磁阀切换带来的可靠性隐患。利用焓差实验台对系统性能进行了实验研究。实验结果表明,系统最佳充液率为100%左右。三个工作模式均具备良好的制冷能力,热管模式EER值在20℃温差下达20.8。以济南地区的数据中心为例进行了全年能耗计算,计算结果表明这一新型系统与传统空调系统相比节能40%,有着良好的应用前景。     

两种动力型分离式热管系统的试验研究

针对数据中心自然冷却需求,研究气体动力型分离式热管与液体动力型分离式热管,设计10kW复合空调样机,在标准焓差法试验室进行性能试验。结果表明:当室内外温差达到20℃时,即可利用气体动力型分离式热管替代蒸气压缩式制冷系统(相同制冷量),实现节能8%~10%;当室内外温差达到30℃时,液体动力型分离式热管系统制冷量可以达到设计指标,能效比EER为8.3,气体动力型分离式热管系统能效比EER为7.4;动力型分离式热管可以改善制冷剂在系统中的分布状态,液体动力型分离式热管可以提高蒸发温度,降低蒸发侧换热温差,气体动力型分离式热管可以提高冷凝温度和冷凝侧换热温差。     

气体增压型复合空调机组研发及全年运行能效分析

针对数据中心机房全天候排热降温需求,提出融合蒸气压缩式制冷循环和气体增压分离式热管循环的气体增压型复合空调机组技术方案,设计额定制冷量为10 kW的复合空调样机,并在焓差试验室进行变工况性能试验。结果表明:当室内外温差大于20℃时,即可采用气体增压分离式热管循环替代常规蒸气压缩式制冷循环(两者制冷量相等),且节能率约为8%;机组的能效比EER与室内外温差近似呈线性趋势增长,当室内外温差为30℃时,其节能率达到70%;其全年能效比AEER比常规蒸气压缩式机房空调高40%。该技术为数据中心、信息基站等高发热量空间的低成本、高能效控温需求提供新的途径。     

Performance representation of variable-speed compressor for inverter air conditioners based on experimental data

Variable speed control of compressors is one of the best methods to regulate the capacity of heat pumps and air conditioners. An analysis is conducted for modeling the variable speed compressor for simulation of inverter air conditioner and heat pump. Having scattered the real operation performance of inverter compressor into infinite operation performance of constant speed compressor, the map-based method is utilized to fit the performance curves of inverter compressor. The model is built at the basic frequency and the map condition as the second-order function of condensation temperature and evaporation temperature. Then it is corrected by the compressor frequency as the second-order function of frequency and by the actual operating condition as the actual specific volume of the suction gas. This method is used to set up simulation models of three different compressors. Compared with the data provided by the compressor manufacturers, the average relative errors are less than 2, 3 and 4% for refrigerant mass flow rate, compressor power input and coefficient of performance (COP), respectively. This model of variable speed compressor is suitable for the simulation of inverter air conditioner and heat pump systems. Based on the experimental data and simulation model, the frequency at zero mass flow rate and power input at zero frequency are discussed and the relation between COP and compressor frequency is analyzed.     

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。     

转子压缩机与涡旋压缩机的对比与发展

空气源热泵压缩机的性能是适合不同气候条件的热泵的关键。本文回顾了转子与涡旋压缩机的发展历程,早期房间空调器用压缩机为活塞式,后期出现了转子压缩机和涡旋压缩机,压缩机效率得以提升。转子式压缩机和涡旋式压缩机均向适应低环境温度工况的方向发展。介绍了影响这两种压缩机发展的关键技术,改进电机与压缩机的结构来提升压缩机效率,通过变压比、喷气增焓、部分负荷下调节等技术,提升了压缩机系统性能系数COP与综合部分负荷性能系数IPLV(H)。采用直流电机替代交流电机,可提高两种压缩机的电机效率和频率调节范围。通过对涡旋压缩机进行不对称涡旋盘设计,可减小噪音与泄漏量;对转子压缩机的双转子进行对称布置,增大了压缩机的容量。带排气阀的涡旋压缩机可在一定程度上实现变压缩比,而转子式压缩机有排气阀,在变工况方面具有明显的优势。两种压缩机均可采用喷气增焓技术,实现热泵低环境温度较大的压缩比。     

制冷系统湿压缩时吸气干度控制方法的实验研究

不完全湿压缩能大幅度降低压缩机排气温度,然而该应用的最大难点是如何控制实时压缩机吸气干度在合适的范围内。本文提出了假拟饱和等熵压缩排气温度控制压缩机吸气该干度的方法,理论分析了在AHRI(空调供暖制冷协会)空调和低温制冷两种典型工况下,R22、R32、R134a和R410A四种制冷剂作为冷媒时,应用该方法控制压缩机吸气带液时系统性能的变化,并通过R32实验验证该结论的正确性。结果表明:利用假拟饱和等熵压缩排气温度可以将压缩机吸气状态控制在少量湿蒸气的状态;在T-s图上具有钟型饱和线形状的R32制冷剂,利用假拟饱和等熵压缩所控制的制冷系统,当吸气干度在0.96~1时,制冷量和COP均能达到最大值。     

基于制冷剂泄出的涡旋压缩机容量调节技术

具有固定内容积比的涡旋压缩机存在当外压缩比小于其内压缩比时内容积效率较快下降的问题,由于空调制冷(热泵)系统大部分时间运行在偏向小室内外温差工况即小压缩比工况下,此时压缩机处于过压缩工况,故制冷(热泵)系统的效率低下;同时,随着系统压缩比的减小,会出现建筑的供冷/供热负荷下降和系统的供冷/供热能力上升的矛盾,系统存在降容的需求。为解决小压缩比工况下压缩机效率降低和系统容量过大的问题,提出一种带制冷泄出功能的涡旋压缩机制冷系统,采用模拟分析和实验测量方法,对其技术可行性进行研究,结果显示:合理适度的制冷剂泄出能有效提高压缩机在过压缩工况下的内容积效率,提高系统的COP并减小制冷系统的制冷/制热能力,是一项极具潜力的制冷系统调节技术。     

Performance of a scroll compressor with vapor-injection and two-stage reciprocating compressor operating under extreme conditions

The current paper presents a comparative study between a scroll compressor with vapor-injection (SCVI) and a two-stage reciprocating compressor (TSRC) operating under extreme conditions. The present work is divided into two parts: in the first part, both compressors are compared in terms of compressor efficiency, volumetric efficiency, coefficient of performance (COP), and cooling capacity with R407C refrigerant; in the second part, the seasonal performances of both compressors working in cooling and heating modes are estimated and analyzed. Results show that the SCVI presents better efficiency and COP than the TSRC for pressure ratios below 7.5. This compressor can be used in air conditioning systems and heat pumps which work under moderate temperature conditions. For higher pressure ratios, the TSRC has better efficiency which subsequently gives higher COP. This type of compressor is more suited to be used in sanitary hot water systems operating in harsh climates and in low-temperature freezing systems (under −20°C).     

基于PLC和变频器的水源热泵节能控制系统

水源热泵作为一种用地下恒温水源代替冷却塔的高效节能空调,在实际应用中,还应充分考虑主机、冷水泵和冷却水泵等消耗能量设备的节能问题。本文重点阐述了水源热泵系统中冷水和冷却水系统的变频节能原理、闭环节能控制方案和对控制系统的设计。     

Evaluating the possible configurations of incorporating the loop heat pipe into the air-conditioning systems

The possible configurations of incorporating the loop heat pipe into the air-conditioning system to perform the reheat process are introduced and evaluated. The results show that the coefficient of performance of the system can be improved and the energy required by the compressor can be reduced when LHP is used instead of the heating element. For low room sensible heat factor, using loop heat pipe can improve the COP by approximately 2.1-fold over that when heating element is used. The results also show that the possible configurations of incorporating the loop heat pipe considered for small air-conditioning unit have the same COP, and among the possible configurations used in air-handling unit. The configuration where the loop heat pipe evaporator is placed in the supply air passage gives the highest COP followed by that where the loop heat pipe evaporator is placed in the return air passage then that where the loop heat pipe evaporator is placed in the passage of the outside air.     

Hybrid liquid desiccant air-conditioning systems: A conceptual study with respect to energy saving potentials

In conventional air-conditioning systems with vapour compression cycles the dehumidification is realised by cooling the air below the dew point of the supply air. One possibility to avoid cooling the air below the dew point and thus to reduce the electric energy demand of air-conditioning systems is hybrid liquid desiccant air-conditioning systems (HLDACS) which use an open absorption cycle for dehumidification of the air. This conceptual study examines four different HLDACS with respect to their electric energy demand and shows energy saving potentials compared to a conventional air-conditioning system for three different climatic design conditions. All considered systems consist of an open absorption system in combination with either a vapour compression system (VCS) or an indirect evaporative cooling system. The results show that electric energy savings of 30–60% depending on the HLDACS and climates are possible.