Operating performance of novel reverse-cycle defrosting method based on thermal energy storage for air source heat pump

To solve the fundamental problem of insufficient heat available during defrosting while ensuring the efficient and safe system operation for air-source heat pumps (ASHPs). A novel reverse-cycle defrosting (NRCD) method based on thermal energy storage to eliminate frost off the outdoor coil surface was developed. Comparative experiments using both the stand reverse cycle defrosting (SRCD) method and the NRCD method were carried out on an experimental ASHP unit with a nominal 2.5 kW heating capacity. The results indicate that during defrosting operation, using the NRCD method improves discharge and suction pressures by 0.24 MPa and 0.19 MPa, respectively, shortens defrosting duration by 60%, and reduces the defrosting energy consumption by 48.1% in the experimental environment, compared with those by the use of SRCD method. Therefore, using the NRCD method can shorten the defrosting duration, improve the indoor thermal comfort, and reduce the defrosting energy consumption in defrosting.

Development and Experimental Study of Air Source Heat Pump Water Heater

The principle and development prospect of air source heat pump water heat were introduced,as well as the designation of condenser (storage water tank),experimental study on installations was also carried out.The results showed that air source heat pump water heater was superior to conventional system.Under the operation of cooling and heating,heat pump comprehensive utilization equipment could improve heating performance,reduce energy consumption,and recycle condensing heat to provide hot water.

Modeling and Optimization of Solar Collector Design for the Improvement of Solar-Air Source Heat Pump Building Heating System

To enhance system stability,solar collectors have been integrated with air-source heat pumps.This integration facilitates the concurrent utilization of solar and air as energy sources for the system,leading to an improvement in the system’s heat generation coefficient,overall efficiency,and stability.In this study,we focus on a residential building located in Lhasa as the target for heating purposes.Initially,we simulate and analyze a solar-air source heat pump combined heating system.Subsequently,while ensuring the system meets user requirements,we examine the influence of solar collector installation angles and collector area on the performance of the solar-air source heat pump dual heating system.Through this analysis,we determine the optimal installation angle and collector area to optimize system performance.

Operation Performance of Air Source Heat Pump System for Space Heating in Tianjin

An air source heat pump system (ASHPS) used in an office building is set up and studied experimentally. Its operating performance in winter is evaluated based on test data and a comparative discussion is given on the effect of climate conditions and heating load ratio on the operation behavior. Then heating capacity variation caused by evaporator frosting is analyzed as well. Finally, the defrosting parameters and the technical feasibility are studied for a constant heating demand. The experimental results indicate that both the outlet water temperature drop and the system COP should be taken into account when setting defrosting parameters, and ASHPS is a viable technology for space heating and hot-water production in winter in Tianjin, which can maintain the room temperature above 19 ℃ when the outdoor temperature is -2 ℃.

Research on Operation Optimization of Heating System Based on Electric Storage Coupled Solar Energy and Air Source Heat Pump

For heating systems based on electricity storage coupled with solar energy and an air source heat pump(ECSA),choosing the appropriate combination of heat sources according to local conditions is the key to improving economic efficiency.In this paper,four cities in three climatic regions in China were selected,namely Nanjing in the hot summer and cold winter region,Tianjin in the cold region,Shenyang and Harbin in the severe cold winter region.The levelized cost of heat(LCOH)was used as the economic evaluation index,and the energy consumption and emissions of different pollutants were analyzed.TRNSYS software was used to simulate and analyze the system performance.The Hooke-Jeeves optimization algorithm and GenOpt software were used to optimize the system parameters.The results showed that ECSA systemhad an excellent operation effect in cold region and hot summer and cold winter region.Compared with ECS system,the systemenergy consumption,and the emission of different pollutants of ECSA system can be reduced by a maximum of 1.37 times.In cold region,the initial investment in an air source heat pump is higher due to the lower ambient temperature,resulting in an increase in the LOCH value of ECSA system.After the LOCH value of ECSA system in each region was optimized,the heating cost of the system was reduced,but also resulted in an increase in energy consumption and the emission of different pollutant gases.

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.

Performance and Optimization of Air Source Heat Pump Water Heater with Cyclic Heating

A new type of microchannel condenser applied in the air source heat pump water heater(ASHPWH)with cyclic heating was proposed in this study.The operating performance of the ASHPWH was frst tested.Then,the structure of the microchannel condenser was optimized with the implement of vortex generators.Finally,a numerical model of the ASHPWH was established and the optimized microchannel condenser was studied.The experimental results showed that the average coefficient of performance(COP)of the 1HP(735 W)ASHPWH reached 3.48.In addition,the optimized microchannel condenser could be matched with a 3 HP(2430W)ASHPWH with an average heating capacity of 10.30 kW,and achieving an average COP of 4.24,14.6%higher than the limit value in the national standard.

太阳能-空气源热泵牧草干燥系统制热性能研究

以太阳能-空气源热泵牧草干燥系统为研究对象,通过系统不同工作模式的温升、恒温制热试验及带载试验,分析了温升速率、单位温升能耗、COP及除湿效率。研究结果表明:联合制热模式与太阳能单独制热相比,单位温升耗电量降低了86.2%,温升速率提高了99~112倍。联合制热模式与热泵单独制热试验相比,在温升过程中温升速率降低了7.7%~17.6%,单位温升耗电量降低8.0%;在恒温制热过程中,前者COP比后者提高了6.5%~11.1%,耗电量降低了5.8%~10.7%;在升温制热过程中前者COP比后者提高了6.0%~10.4%,耗电量降低了6.6%~11.1%。联合干燥模式比热泵单独干燥模式的SMER值高19.8%~36.2%。

基于ANFIS的太阳能-空气源热泵供暖系统温度控制研究

针对太阳能-空气源热泵供暖系统运行环境复杂多变,模糊控制器的设计高度依赖人工经验的问题,提出一种基于自适应神经模糊推理系统(ANFIS)改进的模糊控制方法。该方法利用ANFIS在复杂系统建模中的优势,结合供暖系统温度响应特性和实际运行数据,建立联合供暖系统变工况ANFIS模型,生成与系统性能适配的模糊规则库并传递给模糊控制器执行。Matlab/Simulink仿真对比试验表明,与单一的模糊控制相比,该方法的控制精度提高了17.65%,调节时间缩短了36.4%,具有更高的控制精度和响应速度。

太阳能-空气源热泵热水系统新型组合优化设计

太阳能-空气源热泵热水系统(solar-air source heat pump hot water system, SAHWS)常用于宿舍楼宇供暖,通过对系统参数的优化设计可显著提高系统能效性能与环境友好性。为得到一种综合考虑SAHWS经济、能源、环保与节能的优化方法,提出了一种新型组合优化设计策略,并利用TRNSYS软件搭建系统仿真模型,以西安、西宁、拉萨这3座不同太阳能资源等级城市为例,对SAHWS运行工况对比分析。结果表明:与常用生命周期成本设计相比,所提出的组合优化设计不仅降低了系统成本,还有着较低的系统能耗;组合优化设计的热泵能耗与工作小时数最短,且有最低的热损,在投资成本、系统季节性能因子、太阳能保证率以及碳粉尘、二氧化碳排放量均有较好表现。

电磁-机电暂态混合仿真在多能源系统动态建模中的应用研究

热力网络是多能源系统的重要组成部分。电网和热网建模机理和时间尺度存在较大差异,传统电力系统暂态仿真程序难以直接应用于电-热多能源系统动态仿真。根据电-热类比方法,采用基本电气元件构建了热力管道热路和水路等效电路模型。同时,基于查表法构建了计及设备运行特性的空气源热泵等效电路模型。为提高仿真效率,进一步提出了基于电磁-机电暂态建模框架的电-热多能源系统动态仿真方法。电网采用机电暂态建模,热网采用电磁暂态建模,空气源热泵模型作为接口模型,完成电网模型和热网模型之间的数据交互。电网模型与热网模型均采用毫秒级及以上仿真步长,实现了高效的多能源系统动态仿真。最后通过算例分析验证了所提模型和仿真方法的有效性。

高校宿舍太阳能-空气源热泵复合热水系统设计与应用探讨

在当前积极倡导节能减排的政策要求下,可再生能源利用逐渐普及。以西安建筑科技大学学生宿舍太阳能-空气源热泵复合热水系统为例,阐述了复合热水系统的构成、工作原理,对太阳能集热系统、空气源热泵换热系统、热水供水系统等进行了设计计算,给出了集热器、热泵机组、集热水箱、供热水箱等主要设备的选型结果,提出了系统运行控制方案,并结合实际运行工况下的热性能数据,计算得到系统在不同季节的太阳能保证率、热泵能效比COP值,表明系统具有极大的节能性。

“空气源热泵-太阳能”热水系统在高校学生公寓的应用

学生公寓热水需求量大且用水时间较为分散,选择少污染且高效的热源形式,对高校的节能减排有重要的意义。空气源热泵辅助太阳能热水系统水温恒定,可全天候供应热水,满足阴雨天及冬季使用热水需求,智能化程度高,节能效果明显且项目回收周期短,可以在高校中推广使用。介绍山东某高校公寓实际运行的空气源热泵辅助太阳能热水系统及其控制原理;并通过对电热水器和单独采用空气源热泵制取热水方式的年耗电量计算,与实际运行项目的年耗电量比较,对其节能性进行分析。由于对系统各设备的启停采用了智能控制系统,能够对系统运行模式进行灵活调控,使得该系统比电热水器节电75%,比独立空气源热泵系统节电30%。根据2021年项目实际年收入,预计该系统回收周期为4.2年。

空气源热泵-燃气锅炉联合供暖系统的研究

提出空气源热泵-燃气锅炉联合供暖方案,建立数学模型进行负荷计算和能源系统配置,并对系统的运行费用及全生命期费用进行分析。结果表明,空气源热泵加热功率占总负荷的百分比为83%时性价比最高,全生命期费用最低,与原燃气蒸汽锅炉供暖方案相比,每年可节省32.81万元运行费用,降低的能耗相当于328t标准煤,本方案设计思路可为同类型项目提供一定参考。

直膨式太阳能-空气双源热泵全年运行性能及逐时工作模式优化

该文基于能量平衡与集热/蒸发器换热特性建立双源热泵的系统仿真模型,该热泵采用并联的翅片管风冷蒸发器和吹胀板双面太阳能集热/蒸发器,模型考虑吹胀板蒸发器的正面和背面的实时太阳辐射得热,基于全年气象参数,对热泵在上海地区的全年运行性能进行模拟,分析太阳能集热面积对热泵性能的影响;基于优化的集热/蒸发器面积,对比分析双源热泵3种工作模式的全年运行性能;以逐时热泵COP最高为目标,得到热泵逐时最佳工作模式。模拟结果表明:对于45°朝南安装的双面吹胀板蒸发器,背面太阳能辐射得热是正面得热的3%~15%;双源热泵并联运行模式下全年COP比单空气源热泵、单太阳能热泵分别高24.2%和2.5%;得到以水平总辐照度I_(g)和环境温度T_(a)表示的双源热泵逐时最佳工作模式判别规则:I_(g)>25.05Ta-146.8时,系统的最佳工作模式为太阳能模式;I_(g)<25.05Ta-146.8时,系统最佳工作模式为太阳能-空气源并联模式。在逐时最佳工作模式下,相对于固定的双源并联运行模式,热泵年COP提高4.7%,冬季COP提高11.0%。

夏热冬冷地区太阳能-空气源热泵耦合系统优化设计

为了能够有效地优化夏热冬冷地区太阳能-空气源热泵耦合系统,为节能减排提供支持。本论文对系统的产热性能进行了TRNSYS模拟分析,模拟运行策略优化模型的准确性和合理性。本研究可对太阳能-空气源热泵耦合系统的理论研究和实际应用提供重要指导。

太阳能--地源热泵复合系统应用研究

针对夏热冬冷地区宾馆建筑,本文提出一种太阳能-地源热泵复合系统运行方案用于供冷、供暖和全年供给生活热水。利用TRNSYS软件对宾馆建筑的空调系统和生活热水系统运行性能进行模拟分析,结果表明该复合系统能效比较高,可为太阳能-地源热泵复合系统在夏热冬冷地区宾馆建筑中的推广应用提供参考。

空气-土壤蓄热式热泵系统的实测与模拟研究

为解决寒冷地区单供暖土壤源热泵系统运行引起的土壤热失衡问题,在邯郸某小区土壤源热泵系统的基础上,增设空气换热机组,构成空气-土壤蓄热式热泵系统。利用实测数据对蓄热季典型工况下地埋管进出口水温、蓄热量进行分析,结果显示室外气温较高时,地埋管进口水温和蓄热量较高,有利于地埋管蓄热。利用Trnsys软件建立系统仿真模型,分析不同因素对土壤温升的影响,模拟结果表明:适当增大空气换热器换热面积、空气流量均可提高土壤温升值,但温升趋势逐渐趋于平缓。当空气换热器传热系数为40.0 W/(m^(2)·K),土壤目标温升为3.0℃时,依据土壤温升的拟合曲线得到2个方案:方案1,空气流量150×10^(3)m^(3)/h,空气换热器面积9 494.4 m^(2);方案2,空气换热器面积13 494.4 m^(2),空气流量105×10^(3)m^(3)/h。方案1和方案2每延米地埋管分别需要对应匹配0.086 m^(2)和0.123 m^(2)的空气换热器面积。空气-土壤蓄热式热泵系统连续运行10 a后,方案1和方案2的土壤温度分别下降0.23℃和0.21℃,2个方案单位供暖面积费用分别为13.85元和12.67元,方案2优于方案1。

空气源热泵-散热器供暖系统用于北京地区某农村住宅的实测分析

实测了北京市某农村住宅空气源热泵-散热器低温供暖系统运行期间各房间空气温度、散热器供回水温度及表面温度、系统供热量、耗电量。结果表明,该系统能满足室内热舒适环境的要求,具有供回水温度低、供回水温差小的特点,测试期内系统的COP约为2.8,与传统的电锅炉-散热器供暖系统相比具有良好的节能优势。

HFO-1234ze在空气源热泵热水器中替代R417A、R22的研究

首先从热物性、ODP、GWP、工质毒性、可燃性方面对HFO-1234ze、R417A、R22三种制冷剂进行对比,并进行理论计算,初步分析HFO-1234ze制冷剂运用在空气源热泵热水器上的可行性。然后,在焓差法实验室内,对分别采用HFO-1234ze,R417A和R22作为制冷工质的空气源热泵热水器进行名义工况下的性能测试,对三种制冷剂的吸排气温度,吸排气压力,压缩机输入功率、制热量、性能系数进行对比分析。本文研究结果显示HFO-1234ze可以作为R417a与R22在热泵热水器中的替代制冷剂。此次研究为热泵热水器的工质选择提供参考。