﻿ 基于R448A的高低温试验箱制冷系统特性实验研究

# 基于R448A的高低温试验箱制冷系统特性实验研究Research on Characteristics of Refrigeration System of High and Low Temperature Test Equipment Based on R448A

Abstract: In this paper, a high and low temperature test equipment was built to study the performance comparison of R404A with or without a regenerative cycle. On this basis, the new refrigerant R448A refrigeration cycle was studied. The variation characteristics of the charge volume on the evaporating temperature, cooling capacity, COP and other system performance parameters are analyzed. The results show that at the evaporation temperature of −25˚C, the COP of the R404A refrigeration cycle with regenerator is increased by 25.19% compared with the cycle without re-generator; the COP of the R448A cycle is increased by 3.72% than that of the R404A cycle. With the increase of the charge, the evaporation temperature gradually increases, while the cooling capacity and COP showed a trend of first increasing and then decreasing. When the charge volume is 240 g and the ambient temperature is 20˚C, the difference in cooling capacity between the R448A refrigeration system and the R404A refrigeration system is the largest, with a value of 123.61 W. When the ambient temperature rises from 15˚C to 25˚C, the average drop in COP of the R448A re-frigeration cycle is 11.96%, and the average drop in COP of the R404A refrigeration cycle is 25.84%, indicating that the high temperature stability of the R448A refrigeration system is better than that of the R404A refrigeration system.

1. 引言

2. 实验装置及方法

2.1. 实验装置

Figure 1. Schematic diagram of the experimental system

Figure 2. Experimental system test bench

Figure 3. Structure diagram of double-pipe regenerator

2.2. 计算公式

$Q={q}_{0}×{q}_{m}$ (1)

${q}_{m}$ ——压缩机理论质量流量，单位为kg/h。

${q}_{m}=\frac{{q}_{vt}}{{v}_{1}}$ (2)

${v}_{1}$ ——进气口处吸气状态下气体的比体积，单位为m3/kg。

${q}_{vt}=60in{V}_{p}=47.12inS{D}^{2}$ (3)

n——压缩机的转速，单位为r/min；

S——活塞行程，单位为m；

D——气缸直径，单位为m；

V——活塞移动一个行程所扫过的气缸工作容积，单位为m3

Table 1. Compressor parameters

2.3. R404A和R448A理化性质对比

Table 2. Basic properties of experimental working fluid

3. 制冷系统优化和制冷剂性能对比分析

3.1. 制冷系统性能优化研究

Figure 4. Pressure enthalpy diagram with or without regenerator performance comparison

Table 3. Performance parameters with or without regenerator

Figure 5. Diagram of average daily power consumption of R448A and R404A cycles

3.2. 制冷剂对系统性能的影响

R404A和R448A制冷系统的理论循环特性如图6所示，各项性能参数如表4所示。根据表4数据计算可得，当蒸发温度为−25℃时，R448A和R404A系统的过冷度、单位质量制冷量、单位理论功和COP较R404A分别增大了19.5%、28.8 %、23.8 %和4.04%，如表5所示。表明R448A可显著降低系统能耗，提升系统制冷效率。

Figure 6. R448A system and R404A system pressure enthalpy diagram

Table 4. Point pressure enthalpy value of R404A and R448A cycle parameters

Table 5. R404A refrigeration cycle and R448A refrigeration cycle parameter table

4. 实验对比分析

4.1. 充注量对蒸发温度的影响

Figure 7. The influence of refrigerant charge on evaporating temperature

4.2. 充注量对制冷量的影响

Figure 8. The change graph of the influence of refrigerant charge on refrigeration capacity

4.3. 充注量对COP的影响

Figure 9. COP changes with filling volume

5. 结论

1) 当蒸发温度为−25℃，增加回热器，R404A制冷系统的过冷度增加了5.93℃，COP提高了25.19%。

2) 当蒸发温度为−25℃，与R404A相比，R448A制冷系统过冷度增加1.87℃，单位质量制冷量增加了36.71 kJ/kg，COP提高了3.72%。

3) 制冷量、COP都随着充注量的增加呈现为先增加后减小的趋势。在充注量为240 g，环境温度20℃时，R448A制冷系统与R404A制冷系统的制冷量差值最大，值为123.61 W。

4) 当环境温度从15℃升至25℃时，R448A制冷循环的COP降幅平均为11.96%，而R404A制冷循环的COP降幅平均为25.84%，说明R448A制冷系统性能的稳定性优于R404A系统，并且在高温工况下具有更好的制冷效率。

NOTES

*通讯作者。

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