Performance analysis of heat pump based on a new solar air-source heat pump heating system

To further improve the utilization efficiency of solar energy and the performance of solar heat pump heating systems,a new heating mode of a solar air-source heat pump（SASHP）is proposed,and the characteristics and performance of the heat pump part of this new heating system are studied.Based on a SASHP with 10 kW,the mathematical model of this system is built,and the characteristics and performance are concluded from the simulation analysis at different environmental temperatures and output water temperatures.The results show that the performance of heat pumps can be greatly improved based on the new SASHP.When the environmental temperature is 7 ℃,the coefficient of performance（COP）of the air-source heat pump（ASHP）can be increased by 26% at most.This paper sets up a base for further study on the heating system with this new SASHP in the heating season.

Analysis of Power Quality Problems in Large-Scale Application of Air-Source Heat Pump

With the implementation of electric energy alternatives,the large-scale application of electric energy substitution represented by air-source heat pumps has replaced traditional coal-fired heating,which is beneficial for the environment and alleviates air pollution.However,the large-scale application of airsource heat pumps has brought power quality problems such as voltage sags,harmonic pollution,and three-phase imbalance to the distribution network.This paper studies the fixed-frequency and variablefrequency air-source heat pump,introduces its working principle,analyzes the mechanism of its power quality problem.Moreover,the paper establishes a simulation model for the fixed-frequency heat pump and variable-frequency heat pump to connect to the distribution network.This research mainly studies the impact of large-scale fixed-frequency heat pumps on the depth of voltage sags in the distribution network and the impact of large-scale variable-frequency heat pumps on the harmonic content of the distribution network under different penetration rates and uses measured data to verify the reliability of the simulation results.This paper uses experimental data for the first time to verify the real power quality problems of large-scale heat pumps,which can provide a reference for determining the power quality standards for heat pumps connected to the power grid.At the same time,it can also provide a reference for the power quality management of the distribution network that is actually connected to electric heating.

Novel Radiation-Adjustable Heating Terminal Based on Flat Heat Pipe Combined with Air Source Heat Pump

The electrification of building heating is an effective way to meet the global carbon target. As a clean and sustainable electrified heating technology, air-source heat pumps (ASHPs) are widely used in areas lacking central heating. However, as a major component of space heating, heating terminals might not fit well with ASHP in order to achieve both intermittency and comfort. Therefore, this study proposes a novel radiation-adjustable heating terminal combined with an ASHP to achieve electrification, intermittency, and better thermal comfort. Radiant terminals currently suffer from three major problems: limited maximum heating capacity, inability to freely adapt, and difficulty with combining them with ASHPs. These problems were solved by improving the structural design of the novel terminal (Improvement A–E). Results showed that the maximum heating capacity increased by 23.6% and radiation heat transfer ratio from 10.1% to 30.9% was provided for users with the novel terminal. Further, new flat heat pipe (FHP) design improved stability (compressor oil return), intermittency (refrigerant thermal inertia), and safety (refrigerant leakage risk) by reducing the length of exposed refrigerant pipes. Furthermore, a new phased operation strategy was proposed for the novel terminal, and the adjustability of the terminal was improved. The results can be used as reference information for decarbonizing buildings by electrifying heating terminals.

Exploring heating performance of gas engine heat pump with heat recovery

In order to evaluate the heating performance of gas engine heat pump（GEHP） for air-conditioning and hot water supply, a test facility was developed and experiments were performed over a wide range of engine speed（1400-2600 r/min）, ambient air temperature（2.4-17.8 ℃） and condenser water inlet temperature（30-50℃）. The results show that as engine speed increases from 1400 r/min to 2600 r/min, the total heating capacity and energy consumption increase by about 30% and 89%, respectively; while the heat pump coefficient of performance（COP） and system primary energy ratio（PER） decrease by 44% and 31%, respectively. With the increase of ambient air temperature from 2.4 ℃ to 17.8 ℃, the heat pump COP and system PER increase by 32% and 19%, respectively. Moreover, the heat pump COP and system PER decrease by 27% and 15%, respectively, when the condenser water inlet temperature changes from 30 ℃ to 50 ℃. So, it is obvious that the effect of engine speed on the performance is more significant than the effects of ambient air temperature and condenser water inlet temperature.

The noise spectral characteristics and noise reduction schemes of screw air-source heat pump:A case study

The screw air-source heat pump can cause incessant high noise levels during operation,which might hinder adoption of this energy-efficient heat pump.First,acoustic measurements and comparison testing were performed in this research.The measurements revealed that the compressor is the main noise source of the heat pump,and it shows a multipeak frequency distribution and a wide frequency spectrum under different work conditions,with multiple peaks at 63,250,and 1000 Hz.Then,a compressor sound insulation cover with broadband absorption was proposed,and it was experimentally proven that the insulation cover can reduce the maximum sound pressure level of one unit from 89.8 dBA to 79.1 dBA.Third,we proposed several noise reduction strategies and compared their noise reduction effects using computer simulation.The results showed that the noise problem can be effectively improved through the rational design of the sound barrier and the layout and opening options of heat pump.The distance between the sound barrier and heat pump and the sound attenuation due to diffraction ALa exhibit a U-shaped relation.For buildings of different heights,the optimal heights of noise barrier are proposed.The 5.5-meter is the optimal height of the sound barrier for single-story buildings.The conclusions can be applied to other building projects for heat pump noise reduction.

Refrigerant Control Strategies for Residential Air-Conditioning and Heat-Pump System

This paper simulated the optimal refrigerant charge inventory of a refrigeration system in air-conditioning operation and heat-pump operation respectively,and studied the refrigerant control strategies in this system.The void fraction in two-phase fluid region was calculated by Harms model.And based on distributed parameter model and Harms model,the refrigerant charge inventory in condenser and evaporator were calculated and analyzed in air-conditioning conditions and heat-pump conditions,respectively.The calculating results of different refrigerant mass between refrigeration and heating conditions indicate that the optimal refrigerant charge inventory in heat-pump conditions is lower than that in air-conditioning conditions.To avoid the decrease of COP due to the surplus refrigerant in heating conditions,we introduced the liquid reservoir control method and associate capillary control method.Both of them could increase the heating capacity of the air-source heat pump.The difference of optimal refrigerant charge inventory in air-conditioning and heat-pump system can be controlled by the liquid reservoir or the associate capillary.

The Efficiency Analysis of the Exhaust Air Heat Pump System

This paper is based on long term parameter measurements of the exhaust air heat pumps (EAHP) system in a new built apartment building. The building was equipped with an exhaust air ventilation system and exhaust air heat pump for ventilation heat recover. The results of the measurements show that the COP of the EAHP is mainly related to the temperature graph of the heating system and the supply temperature of domestic hot water (DWH). During the measurement period some other impact factors, such as the quality of maintenance, the nighttime temperature graph of the heating system, the reduction of the exhaust air flows in case of low temperatures, mistakes in designing and low building quality, have also played a role. An analysis of energy consumption shows that in winter conditions the COP is about 3.0 and in the transition period about 3.3. The energy recovery value of the EAHP is 0.5.

大滑移温度CO_(2)非共沸工质余热回收热泵热水系统实验研究

通过热泵技术将生产/生活中的低品位余热提质增效具有广泛的应用潜力。其中,非共沸工质能够实现热泵循环换热过程中的温度匹配,实现余热资源的深度利用。基于水源热泵热水实验台对基于大滑移温度的CO_(2)/R1234yf、CO_(2)/R290、CO_(2)/R600a和CO_(2)/R32非共沸工质进行实验分析,并以R290工质作为对照,研究蒸发器与冷凝器同时满足大温差情况下的热泵性能表现。结果表明:非共沸工质充注量主要影响循环过冷度,进而影响系统COP,当CO_(2)/R1234yf的质量分数为15%/85%时,循环存在最优充注量,在实验工况(热源进水温度25℃,出水温度5℃;热汇进水温度15℃,出水温度45℃)下最优充注量对应的COP为7.66。同时,在实验工况下,相较于R290单工质,CO_(2)/R290工质对最优COP提升了75.2%,对应q v(单位容积制热量)提升了107.7%;CO_(2)/R1234yf工质对最优COP提升了27.7%,对应q v提升了92.0%;CO_(2)/R32工质对最优COP提升了15.0%;而CO_(2)/R600a工质对最优COP仅提升1.7%,应用潜力较低。

考虑空气源热泵负荷聚合参与的需求响应

基于“电网-聚合商-负荷”三级架构,提出空气源热泵负荷聚合参与需求响应的控制策略。供暖运营商作为热泵负荷的聚合商,在保证用户热舒适度的基础上,利用建筑本身的蓄能能力,结合分时电价最小化供热成本,并对负荷可调节潜力进行评估。当电网调度部门下发调控指令后,考虑用户舒适度和电网调节需求,基于多目标遗传算法分配各负荷调节量,在满足调控目标的同时可改善调控带来的聚合功率振荡、反弹负荷大等问题。最后,仿真验证所提策略的有效性。

利用数据中心余热供热的系统设计与分析

数据中心余热供热是提高数据中心能源利用效率和实现冬季清洁供暖的重要途径。本文提出了一种适用于数据中心的长距离供热系统,在热源和热汇处设置多级热泵以增大供热管网供回水温差,并使用储热装置保障数据中心和供热系统的安全性,提高数据中心余热利用率。以张家口某数据中心为例进行了分析,该系统初投资为50.21元/m^(2),运行费用为26.37元/GJ,投资回收期约为5.31 a,具有较好的经济性和节能减排效果。

制热工况下跨临界CO_(2)热泵最优排气压力的影响因素研究

最优排气压力是影响跨临界CO_(2)热泵性能最重要的因素。为研究最优排气压力存在原因及其影响参数,并揭示各参数对最优排气压力的影响机理,基于传热夹点理论对最优排气压力进行了理论分析。利用AMESim软件搭建了考虑气体冷却器内部传热夹点的跨临界CO_(2)热泵模型进行仿真计算,在进水温度为10~40℃、出水温度为60~90℃、环境温度为-30~25℃的宽工况内定量研究了进水温度、出水温度、环境温度及回热率对热泵系统最优排气压力的影响。研究结果表明:进水温度越低、出水温度越低、环境温度越低,均会导致传热夹点向气体冷却器出口移动,从而使系统的最优排气压力减小;同时,采用回热方式也能够将传热夹点进一步向气体冷却器出口推移,从而减小最优排气压力。研究结果证实传热夹点的位置对于系统最优排气压力的取值具有重要影响,因此基于传热夹点的分析与设计方法具有更强的适用性,可为热泵供暖、车辆热管理等用途中CO_(2)热泵系统的设计和性能优化提供理论与工程基础。

电动工程机械双热源热泵空调系统的仿真和试验

热泵空调系统是电动汽车新型加热取暖方式之一,具有制热制冷效率高、控制方便等优势,其在电动工程机械领域也有良好的应用前景。但热泵空调系统最大的应用难题是其利用的冷媒R134a在低温环境温度下,由于制冷剂本身性质的限制及室外侧换热器结霜现象,导致系统的制热性能严重下降,进而影响热泵空调系统的综合性能。据此,提出了基于双热源热泵空调的纯电工程机械整车热管理系统的解决办法,引入工程机械的电驱系统余热作为电驱源,与传统热泵空调的空气源组成双热源热泵空调系统,通过系统中余热的合理运用,提高能量利用率。AMESim仿真和热管理试验平台不同模式下的试验结果表明,电驱源热泵系统的制热性能明显优于传统空气热源热泵,有效提高制热能效系数。

吸收-压缩热泵回收高水分杂醇烟气余热研究

为了处理煤化工过程中产生的有害副产杂醇并回收热能,本文设计了一台以杂醇为燃料的热水锅炉,并在锅炉尾部加装了一种新型吸收-压缩复合热泵来回收烟气余热,通过Aspen Plus软件对热泵回收烟气余热流程进行模拟。结果表明杂醇烟气蕴含丰富潜热,采用该新型热泵能实现余热有效回收,额定工况下能使锅炉热效率提高11.01%。进一步研究了压缩机压比、回水温度和锅炉负荷对热泵性能的影响,并提出分别基于节能和碳减排效果的热泵性能系数COP_(a)和COP_(e)来全面分析热泵的运行性能。结果发现在压比为9.6时热泵COP_(a)和COP_(e)最高,且在压比小于9.6时,热泵性能会受回水温度升高的影响较大。随着锅炉负荷的增大,热泵系统的COP_(a)和COP_(e)先增大后减小。本文研究可为高水分烟气余热的深度回收和新型复合热泵的应用提供一些理论依据。

余热回收型空气源热泵烘干系统设计与能效实验

采用电能空气源热泵替代传统的木柴燃烧进行经济农作物烘干具有节能环保、降本增效等优点。针对空气源热泵烘干过程中热量随高温空气流失而降低了能源利用率的问题,设计了一款余热回收再利用的空气源热泵烘干系统,首先通过调节新风阀与回风阀开度使热风在烘干机内持续循环;然后通过热回收器与热泵将排出的高温空气余热回收,可显著提升热能的利用效率。为量化空气源热泵的电热转换与烘干加热过程能源利用率,研究了两级能效指标。一级能效指标可衡量电热转换与回收的利用效率;二级指标可直接衡量电能对产量的产出效率。研制了余热回收型空气源热泵烘干样机系统,并设计了一套远程监控系统,可在云端和手持终端实时在线监控作业过程和状态,控制烘干作业的工艺流程,并计算两级能效指标。食用菌烘干实验结果表明:该余热回收型空气源热泵烘干系统样机的一级能效指标为84.69%、二级指标为4.37 kg/(kW·h),具有能效利用率高、安全可靠等优点。

多级余热回收空气能热泵系统效能的实验研究

针对热风干燥用空气能热泵系统废热回收不充分,造成热泵系统换热效率低下、低温环境工作适应性差等问题,基于空气源热风系统自由热回收和自由热分配的技术方法,设计开发了多级余热回收空气能热泵系统。实验测试结果表明:余热回收可以有效提升热风干燥用空气能热泵系统的热效率,最高可达无回热运行模式下热泵能效比COP的1.51倍;环境温度对余热回收模式的选择有决定性影响;当环境温度一定时,制热温度上升则热泵系统COP下降,但是不同余热回收模式提升热泵系统效能的优劣性不随制热温度变化;当实验工况及余热回收模式一定时,热泵系统COP与新风量存在极值关系。

岩棉工业余热回收热泵系统动态仿真与性能分析

以陕西某岩棉厂为研究对象,基于Modelica语言建立岩棉厂余热回收热泵供暖系统的仿真模型,开展系统运行特性研究、经济性分析和碳排放计算。结果显示:负荷率越高,余热回收热泵系统的能效比(COP)越高;项目静态回收期在4年以内;与空气源热泵、燃气锅炉相比,余热回收系统的碳排放分别减少了37.24%、34.25%,证明该余热回收系统具有节能减排效益。

基于热泵技术的余热回收供热系统

传统热电厂的循环冷却水中含有大量的低品位余热,利用热泵技术对其进行回收,能够显著提升供热系统的能源利用效率,有利于实现节能减排和“碳中和”目标。设计基于单、双吸收式热泵机组的余热回收供热系统,旨在有效利用循环冷却水中的余热,增加供热能力并分析系统性能。结果表明,与传统供热系统相比,两种余热回收供热系统均可显著回收循环冷却水的热量,提高系统供热量并大幅减少能源消耗,带来可观的经济收益;双吸收式热泵机组系统展现出更优异的热力性能,具备显著的节能减排优势。分析循环冷却水入口温度和一次网回水温度对双吸收式热泵机组性能的影响,发现循环冷却水温度对系统性能影响较大,随着循环冷却水温度的升高,系统的供热量增加比例、节约标煤量和新增供热面积均增加,而一次网回水温度对系统性能的影响较小,随一次网回水温度的升高,系统的供热量增加比例、节约标准煤量和新增供热面积几乎不变。

基于余热回收的吸收式热泵系统在热电厂的节能环保效益

以某热电厂为调研对象,根据厂区的余热资源和冷热负荷需求,提出了一套基于余热回收的蒸汽型吸收式热泵系统。该系统在冬季回收脱硫塔循环水中的余热用于厂区内的建筑供暖和加热锅炉补水,并在夏季利用20℃的锅炉除盐水作为冷却剂,回收建筑得热。采用EnergyPlus软件构建了原有空调系统和余热回收系统的能耗模型,以一个模拟周期为例,对比分析了两者在能耗、运行费用、环保效益等方面的差异。结果表明,该系统每年可回收热量2656GJ、节省标煤3.79t、减少CO_(2)排放18.53t,节能环保效果显著。

回收低温余热的热电耦合电解制氢系统及性能评估

固体氧化物电解制氢时,水以气态进行电解,但仅依靠电解产物冷却所释放的热能不足以将液态给水蒸发气化,电解制氢系统存在供热缺口。为解决该问题,基于高温热泵技术,提出了通过热泵吸收外界低温余热(<100℃)制取较高温热能(>100℃),以满足给水蒸发气化用热的系统工艺方法,设计了系统流程,研究了热泵系统关键参数对系统性能的影响,并通过建模仿真的手段评估了该系统的制氢性能。研究结果表明:①利用热泵吸收环境中的低温余热,制取较高温热能使电解给水蒸发,具有技术可行性,该方法同样适用于系统内部电解产物所携带余热的回收再利用;②外界余热温度越高,越有利于降低系统的制氢能耗,直流电解功率为1 MW的电解制氢系统,对余热源的热需求约为138 kW;当余热源为水且温降在5℃时,水的需求量约为20 t/h;③假设外界余热不计入制氢能耗,利用热泵集成外界余热时,系统理论单位制氢能耗约3.5 kW·h/m^(3),全部为电能消耗。结论认为,通过热泵吸收低温余热向高温电解制氢系统供热的系统工艺,开辟了一种低品位余热向高品位氢能转化的新思路、新途径和新方法,具有广阔的应用前景。

基于热集成的轻烃回收装置气体分馏系统用能优化

针对轻烃回收装置气体分馏系统进行模拟分析与用能优化,并基于Aspen Plus流程模拟,探讨了进料温度、回流比对系统能耗的影响。考虑到炼化低温余热相对富余,结合工艺分析和精馏序列优化,并改善热源、热阱的不匹配性,降低脱乙烷塔和脱丁烷塔塔底温度,提出了集成热媒水系统、热泵系统的气体分馏改进工艺以降低装置能耗,并对改进前后的能效和经济性进行了对比分析。结果表明:4种改进方案均可降低气体分馏系统能耗15.61%以上,年净效益151.80万元以上。集成热媒水系统的改进工艺㶲耗量降低0.52 MW,降幅达40.95%,年净效益400.57万元,投资回收期为0.42 a。集成直接式热泵系统的改进工艺方案改进效果最佳,过程㶲耗量降低0.67 MW,降幅达53.04%,年净效益498.18万元,投资回收期为1.41 a。