Research on the total heat recovery characteristics of fresh air based on modified PVDF membranes

doi:10.11949/0438-1157.20250260

Abstract

Abstract:

Reducing energy consumption in building operations requires energy-efficient management of HVAC fresh air systems. Implementing low-carbon strategies in ventilation systems is critical for sustainable development. The membrane fresh air total heat recovery device has a wide range of application potential in the field of energy saving of fresh air system due to its compact structure and high heat and moisture exchange efficiency. Polyvinylidene fluoride(PVDF) membranes were modified with graphene oxide (GO) and polyvinylpyrrolidone (PVP) to enhance heat-moisture transfer performance. The water vapor transmission rate (WVTR) was rigorously measured, and the effects of membrane composition, surface hydrophilicity, and pore microstructure on moisture permeation mechanisms were systematically analyzed. Experimental evaluations were conducted on heat recovery cores fabricated from the modified PVDF membranes within a fresh air system. The impacts of temperature, relative humidity, and airflow rate on total heat recovery efficiency (THRE) were investigated. A predictive model for THRE was subsequently developed using dimensionless parameters. The results indicate that with 0.1 g GO and 7.0 g PVP additives, the modified PVDF membrane exhibited a contact angle of 39°, achieving a water vapor transmission rate of 3641 g/(m²·d). Compared to commercial membranes, the modified PVDF membranes exhibited 29.7% higher THRE and 33.7% greater total heat recovery capacity (THRC). The dimensionless predictive model demonstrated high accuracy, with deviations from experimental data consistently below ±5%.

Key words: polyvinylidene fluoride, film, energy recovery ventilation, fresh air system, heat exchange efficiency, experimental validation, prediction

摘要：

为降低建筑运行能耗，空调新风系统的绿色低碳运行至关重要。膜式新风全热回收装置因其结构紧凑且热湿交换效率较高，在新风系统节能领域具有广泛的应用潜力。以聚偏氟乙烯（PVDF）为基材，采用氧化石墨烯（GO）和聚乙烯吡咯烷酮（PVP）等材料对其进行改性以强化热湿交换效率。测定了改性膜材料的水蒸气透过率，系统分析了其组分、表面特性及微观结构对水蒸气透过的影响机理。在新风热回收系统中，对改性PVDF膜材料构建的热回收芯体进行了实验研究。分析了温度、相对湿度和风量等因素对装置全热回收特性的影响规律，并建立了全热回收效率的预测模型。结果表明，GO含量为0.1 g、PVP含量为7.0 g时，改性PVDF膜材料接触角为39°，此时水蒸气透过量可提高至3641 g/(m²·d）。与商用膜相比，改性PVDF膜的全热回收效率平均提高29.7%，全热回收量平均提高33.7%。基于无量纲参数构建的预测模型与实验结果的偏差均在±5%以内，具备较高的预测精度。

关键词: 聚偏氟乙烯, 膜, 全热交换器, 新风系统, 换热效率, 实验验证, 预测

CLC Number:

TB 383

Xianxing SONG, Xinyang ZHAO, Guangzhe LIU, Lingjian KONG. Research on the total heat recovery characteristics of fresh air based on modified PVDF membranes[J]. CIESC Journal, 2025, 76(10): 5426-5436.

宋先行, 赵新阳, 刘广哲, 孔令健. 基于改性PVDF膜的新风全热回收特性研究[J]. 化工学报, 2025, 76(10): 5426-5436.

Figures/Tables 15

Fig.1 Thin film preparation process

Table 1 Composite membrane composition information

组别	PVDF/g	DMAc/ml	DMF/ml	PVP/g	PEG/g	GO/g	LiCl/g
M1	13.0	72.0	8.0	7.0	—	—	—
M2	13.0	72.0	8.0	7.0.	—	0.05	—
M3	13.0	72.0	8.0	7.0	—	0.1	—
M4	13.0	72.0	8.0	7.0	—	0.2	—
M5	13.0	72.0	8.0	7.0	—	—	1.0
M6	13.0	72.0	8.0	7.0	—	—	2.0
M7	13.0	72.0	8.0	7.0	—	—	3.0
M8	13.0	69.0	8.0	10.0	—	—	—
M9	13.0	65.0	8.0	14.0	—	—	—
M10	13.0	72.0	8.0	—	7.0	—	—
M11	13.0	69.0	8.0	—	10.0	—	—
M12	13.0	65.0	8.0	—	14.0	—	—

Fig.2 Experimental system

Table 2 Uncertainty calculation results

输入量	测量仪器	测量精度	测量不确定度	最大相对不确定度
温度	温度传感器	±0.2℃	1.2×10^-1K	3.9%
湿度	湿度传感器	±2%	1.2	3.3%
风量（间接测量）	微压差传感器	1%	115.5 Pa	8.7%

Fig.3 Effect of different additives on water vapour permeability

Fig.4 Effect of different pore-forming agents on water vapour permeability

Fig.5 Static contact angle test

Fig.6 Microscopic structure

Fig.7 Effect of temperature change on heat recovery efficiency

Fig.8 Effect of temperature change on sensible heat and latent heat

Fig.9 Effect of relative humidity on heat recovery

Fig.10 Effect of relative humidity on sensible heat and latent heat transfer

Fig.11 Effect of air volume change on heat recovery

Fig.12 Effect of air volume change on sensible heat and latent heat transfer

Fig.13 Comparison of the experimental and predicted values of total heat exchange efficiency

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