复叠式空气源热泵热水器除霜控制方法实验研究
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摘 要
复叠式热泵热水机组可在环境温度为-25℃下制取 80℃的热水，当机组在室
外环境温度低于 5℃运行时，存在结霜和除霜的问题。目前，常规易结霜区域（室
外环境温度在-7℃~5℃）下的结霜和除霜规律研究较多，而对更低室外环境温度
（-18℃~-7℃）下结霜和除霜规律相应的研究较少，因此，本文以复叠式热泵热
水机组为研究对象，研究在较大的室外温度和湿度变化范围内的结霜规律和除霜
控制策略。
首先，通过对我国东北三个城市气象参数分析，发现-18℃~-7℃室外温度下，
室外相对湿度在 70%以上的天气占有一定的比例，由于相对湿度大于 70%时的结
霜风险较大，所以本文主要针对 70%~90%的相对湿度进行研究。
然后，本文将对复叠式空气源热泵热水器在焓差环境室中器机组进行结霜实
验研究，该机组低温级采用 R410A 作为循环工质，蒸发温度可达-40℃。本文所
研究的室外温度范围为-18℃~6℃、相对湿度范围为 70%-90%，共进行了 20 次实
验，获得了结霜特性（即结霜量），以及结霜对机组性能的影响，主要包括结霜
时机组 COP、换热量、耗电量、盘管温度以及高、低温级吸、排气温度和压力等
参数。
除霜试运行实验及除霜实验在结霜实验基础上进行，除霜试运行实验主要为
了获得现有的时间-温差除霜控制方法所需要的控制参数；除霜实验主要为了验证
验证优化后的除霜控制方法以及结霜实验中得到的结霜因子（结霜量与结霜时间
以及盘管温度与露点温度差的比率）。
通过实验研究，本文首先得出结霜量随结霜时间几乎呈线性变化，当结霜量
达到一定程度，将对机组性能产生很大的影响；其次，根据结霜实验总结出带亲
水层的翅片管换热器的结霜因子，其值为 8.58×10-4 kg/(m2·℃·min) ，可以通过它
对机组低温级蒸发器表面的结霜量进行预判；再者，通过除霜试运行实验获得不
同室外环境温度下机组除霜时的各个参数，根据这些参数优化了时间-温差除霜控
制方法，通过几个工况除霜实验发现机组运行良好，没有出现误除霜或除霜不尽
的现象，且机组运行性能均能保持较高状态，除霜后机组的平均 COP 相对机组正
常运行时的 COP 下降不会超过 15%；再者，在除霜实验中发现，当室外温度低
于某一值（实验发现这个临界点在-12℃~-9℃之间）时，热气旁通除霜法除霜将
无法除尽低温级蒸发器上的霜层，之后对出现这种情况的原因进行分析，并给出
采用电加热除霜所需的功率。最后，把结霜实验中总结出的结霜因子作为除霜控
制策略中的一个条件进行除霜实验，并把除霜时间的实验值和理论值进行比较，
发现其差值不是很大，考虑到计算和实验时有很多因素影响除霜时间，因此可以
证明利用结霜因子对除霜进行预判并根据其判断结果进行除霜控制有一定的可行
性。
关键词：复叠式热泵 结霜 除霜方法 除霜控制方法 结霜因子
ABSTRACT
The experimental study of frosting and defrosting features based on the cascade
type air-source heat pump water heater is not only in the easy frosting area(outdoor
temperature is from -7℃ to 6℃), but also in the lower outdoor temperature(from -18℃
to -7℃) in this paper. And the heat water can achieve the goal of the production of 80℃
hot water under -25℃ ambient environment.
First,meteorological parameters of three cities in northeast China have been
analyzed to demonstrate the significance of the study, finding the climate is common
that outdoor temperature is from -18℃ to -7℃and outdoor relative humidity is from
70% to 90%.
The frosting experiment based on the cascade type unit is carried out in the
enthalpy-difference lab.And the water heater includes the low temperature level cycle
and the high temperature level cycle. In the low temperature level cycle, R410A is
used as the refrigerant, while in the high temperature level cycle, R134a is used as the
refrigerant. In addition, the outdoor environmental conditions include that the outdoor
temperature is from -18℃ to 6℃ and outdoor relative humidity is from 70% to 90%
in this experiment. According to the frosting experiment, some parameters would be
obtained, including the coefficient of performance (COP), the amount of heat exchange
and the power of the heat pump unit, the evaporator coil temperature in the low
temperature level cycle and the intake and exhaust gas temperature and pressure in the
high or low temperature level cycle, etc.
Based on the frosting experiment, the trial operation experiment of defrosting is
carried out and the Time-Temperature difference defrosting control method is
optimized. Finally, the optimized control method and the frosting factor (the ratio of
the frosting amount and the frosting-time and the difference of the outdoor temperature
and the evaporator coil temperature in the low temperature level cycle) is also verified
by the following defrosting experiments.
Experimental results are described below. Firstly, the amount of frosting almost
changes linearly with the frosting time, and when the frosting amount reaches a certain
level, the unit performance will be made great influences. Secondly, the frosting factor
generalized in the frosting experiment which is 8.58×10-4 kg/(m2·℃·min) can predict
the frosting amount on the surface of evaporator coil and be used to the starting
condition of defrosting. At the same time, the reasonably and feasibility of the frosting
factor are proved by the comparison of the theoretical and experimental values and the
difference of the theoretical and experimental values is not large. Thirdly, the
Time-Temperature difference defrosting control method which is optimized by the trial
operation experiment of defrosting is imported into PLC of the unit. Then, the heat
pump unit with the new control method is operated and the running results demonstrate
that “the phenomenon of mistaken defrosting or incomplete defrosting” is not found
and the unit operating performance keep well,namely the difference of the average
coefficient of performance after defrosting and the normal coefficient of performance
is not more than 15%. In the end, the shortcoming of the defrosting method of hot gas
bypass is found by the defrosting experiment that when outdoor temperature below a
certain value (the value is located between -12℃ and -9℃), the frost layer on the
surface of the evaporator coil in the low temperature level cycle can be cleaned
incompletely by the defrosting method. To the later convenience of selecting the
electric heating defrosting method, the power of the electric heater is calculated in the
paper.
Key Word: cascade heat pump, frosting, defrosting methods,
defrosting control methods, frosting factor
目 录
第一章 绪论 .................................................................................................................... 1
1.1 课题的来源 ............................................................................................................ 1
1.2 本课题的提出及意义 ............................................................................................ 2
1.3 本领域目前的国内外先进水平 ............................................................................ 2
1.3.1 霜层基本特性研究 ......................................................................................... 3
1.3.2 结霜工况下空气源热泵系统性能研究 ......................................................... 3
1.3.3 除霜及除霜控制方法的研究 .......................................................................... 5
1.4 本章小结 ................................................................................................................ 8
第二章 复叠式空气源热泵热水器的介绍及应用 ........................................................ 9
2.1 复叠式热泵系统的理论循环 ................................................................................ 9
2.2 复叠式空气源热泵系统结构及部件 ..................................................................... 9
2.2.1 复叠式空气源热泵系统结构 .......................................................................... 9
2.2.2 复叠式空气源热泵系统部件 ........................................................................ 10
2.3 复叠式空气源热泵热水器的控制系统 .............................................................. 11
2.4 复叠式热泵热水器的除霜方法 .......................................................................... 14
2.5 复叠式空气源热泵的应用环境 .......................................................................... 15
2.6 本章小结 .............................................................................................................. 18
第三章 实验系统及实验方案 ...................................................................................... 19
3.1 实验系统 ............................................................................................................... 19
3.1.1 焓差环境实验室 ........................................................................................... 19
3.1.2 复叠式空气源热泵热水器 ........................................................................... 20
3.1.3 实验的测量系统 ........................................................................................... 20
3.2 实验方案 .............................................................................................................. 25
3.2.1 实验目的 ........................................................................................................ 25
3.2.2 实验方法 ....................................................................................................... 25
3.2.3 实验工况确定 ............................................................................................... 27
3.2.4 实验测点的确定 ........................................................................................... 27
3.3 本章小结 .............................................................................................................. 29
第四章 复叠式热泵热水器的结霜特性 ...................................................................... 30
4.1 结霜特性 .............................................................................................................. 30
4.1.1 结霜量的计算 ............................................................................................... 30
4.1.2 结霜量随时间的变化关系 ........................................................................... 31
4.2 结霜对机组性能参数的影响 .............................................................................. 35
4.2.1 不同室外环境温度下结霜对机组 COP 和换热量的影响 .......................... 35
4.2.2 不同相对湿度下结霜对机组换热量和 COP 的影响 .................................. 37
4.2.3 结霜对机组高、低温级吸、排气温度的影响 ............................................ 40
4.2.4 结霜对高、低温级吸、排气压力的影响 ................................................... 43
4.3 除霜控制方法判定条件探讨 .............................................................................. 46
4.3.1 室外温度与盘管温差及室外露点温度与盘管温度差随结霜量的变化 ... 46
4.3.2 室外露点温度与盘管温度差作为除霜判断条件理论分析 ....................... 48
4.3.3 结霜因子的提出 ........................................................................................... 49
4.4 本章小结 .............................................................................................................. 50
第五章 复叠式空气源热泵的除霜控制方法实验研究 .............................................. 51
5.1 机组除霜试运行实验 .......................................................................................... 51
5.1.1 机组除霜试运行时的除霜逻辑 .................................................................... 51
5.1.2 试运行时的实验数据处理 ............................................................................ 56
5.2 除霜控制策略的优化 .......................................................................................... 60
5.3 除霜控制策略优化后的机组的运行情况 .......................................................... 65
5.3.1 优化后机组运行性能分析 ........................................................................... 65
5.3.2 优化后机组运行误除霜或除霜不尽的情况分析 ........................................ 70
5.3.3 低温下除霜方法 ........................................................................................... 72
5.4 盘管温度与露点温度除霜控制法理论与实验分析 .......................................... 75
5.4.1 理论分析 ....................................................................................................... 75
5.4.2 实验结果及分析 ........................................................................................... 77
5.4.3 理论计算与实验结果对比 ........................................................................... 78
5.5 本章小结 .............................................................................................................. 79
第六章 结论及展望 ...................................................................................................... 81
6.1 结论 ...................................................................................................................... 81
6.2 今后的工作方向 .................................................................................................. 82
参考文献 ........................................................................................................................ 83
在读期间公开发表的论文和承担科研项目及取得成果 ............................................ 87
致谢 ................................................................................................................................ 88
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作者：牛悦
分类：高等教育资料
价格：15积分
属性：92 页
大小：6.23MB
格式：PDF
时间：2025-01-09
