The liquid refrigerant defrosting (LRD) is a defrosting method which leads the liquid refrigerant in the high-pressure reservoir to the frosting evaporator. The refrigeration process is continuous during the defrosting period, which increases the defrosting frequency. Compared with the traditional defrosting method, no large fin spacing should be left to reduce the defrosting frequency. The system can recover all the defrosting cooling capacity to improve the subcooling, so that the indoor air temperature fluctuations are avoided. In order to explore the effect and the rule of the LRD, the defrosting experiments were carried out in different frosting mass under the condition of the cold storage temperature of −20 °C. The defrosting time, temperature rise value, cooling capacity, and compressor power consumption value were calculated at the different frosting mass. Interpolation and applying the curve fitting equation helps to obtain remaining values. The relative humidity was calculated by the frosting mathematical model. Finally, the relationship between the coefficient of performance (COP) and the defrosting cycle (the sum of the defrosting time and the frosting time) was obtained. The experiments and theoretical research showed that the fluctuating value of cold storage temperature was about 5 °C and the defrosting time was about 30 min during the defrosting process. In the case of the relative humidity of 70%, 80%, 90%, the optimum defrosting cycle of the experiment was 16.4, 10.9, 7.5 h and the frosting mass was 2.66, 2.90, 3.22 kg, and the maximum COP was 1.51, 1.48, 1.45.

References

References
1.
Hermes
,
C. J. L.
,
Piucco
,
R. O.
,
Barbosa
,
J. R.
, Jr
, and
Melo
,
C.
,
2009
, “
A Study of Frost Growth and Densification on Flat Surfaces
,”
Exp. Therm. Fluid Sci.
,
33
(
2
), pp.
371
379
.
2.
Amer
,
M.
, and
Wang
,
C. C.
,
2017
, “
Review of Defrosting Methods
,”
Renewable Sustainable Energy Rev.
,
73
, pp.
53
74
.
3.
Machielsen
,
C. H. M.
, and
Kerschbaumer
,
H. G.
,
1989
, “
Influence of Frost Formation and Defrosting on the Performance of Air Coolers: Standards and Dimensionless Coefficients for the System Designer
,”
Int. J. Refrig.
,
12
(
5
), pp.
283
290
.
4.
Tan
,
H.
,
Tao
,
T.
,
Xu
,
G.
,
Zhang
,
S.
,
Wang
,
D.
, and
Luo
,
X.
,
2014
, “
Experimental Study on Defrosting Mechanism of Intermittent Ultrasonic Resonance for a Finned-Tube Evaporator
,”
Exp. Therm. Fluid Sci.
,
52
(
1
), pp.
308
317
.
5.
Hayashi
,
Y.
,
Aoki
,
K.
, and
Yuhara
,
H.
,
1977
, “
Study of Frost Formation Based on a Theoretical Model of the Frost Layer
,”
Heat Transfer-Jpn. Res.
,
6
(
3
), pp.
79
94
.
6.
Brailsford
,
A. D.
, and
Major
,
K. G.
,
1964
, “
The Thermal Conductivity of Aggregates of Several Phases, Including Porous Materials
,”
Br. J. Appl. Phys.
,
15
(
3
), p.
313
.
7.
Jones
,
B. W.
, and
Parker
,
J. D.
,
1975
, “
Frost Formation With Varying Environmental Parameters
,”
ASME J. Heat Transfer
,
97
(
2
), pp.
255
259
.
8.
Yaqub
,
M.
,
Zubair
,
S. M.
, and
Khan
,
J. U. R.
,
2000
, “
Performance Evaluation of Hot-Gas by-Pass Capacity Control Schemes for Refrigeration and Air-Conditioning Systems
,”
Energy
,
25
(
6
), pp.
543
561
.
9.
Liu
,
Z.
,
Tang
,
G.
, and
Zhao
,
F.
,
2003
, “
Dynamic Simulation of Air-Source Heat Pump During Hot-Gas Defrost
,”
Appl. Therm. Eng.
,
23
(
6
), pp.
675
685
.
10.
Cho
,
H.
,
Kim
,
Y.
, and
Jang
,
I.
,
2005
, “
Performance of a Showcase Refrigeration System With Multi-Evaporator During On–Off Cycling and Hot-Gas Bypass Defrost
,”
Energy
,
30
(
10
), pp.
1915
1930
.
11.
Hu
,
B.
,
Wang
,
X.
,
Cao
,
F.
,
He
,
Z.
, and
Xing
,
Z.
,
2014
, “
Experimental Analysis of an Air-Source Transcritical CO2 Heat Pump Water Heater Using the Hot Gas Bypass Defrosting Method
,”
Appl. Therm. Eng.
,
71
(
1
), pp.
528
535
.
12.
Kim
,
J.
,
Choi
,
H. J.
, and
Kim
,
K. C.
,
2015
, “
A Combined Dual Hot-Gas Bypass Defrosting Method With Accumulator Heater for an Air-to-Air Heat Pump in Cold Region
,”
Appl. Energy
,
147
, pp.
344
352
.
13.
Sherif
,
S. A.
, and
Hertz
,
M. G.
,
2015
, “
A Semi‐Empirical Model for Electric Defrosting of a Cylindrical Coil Cooler
,”
Int. J. Energy Res.
,
22
(
1
), pp.
85
92
.
14.
Alebrahim
,
A. M.
, and
Sherif
,
S. A.
,
2002
, “
Electric Defrosting Analysis of a Finned-Tube Evaporator Coil Using the Enthalpy Method
,”
Archive Proc. Inst. Mech. Eng. Part C J. Mech. Eng. Sci.
,
216
(
6
), pp.
655
673
.
15.
Kwak
,
K.
, and
Bai
,
C.
,
2010
, “
A Study on the Performance Enhancement of Heat Pump Using Electric Heater Under the Frosting Condition: Heat Pump Under Frosting Condition
,”
Appl. Therm. Eng.
,
30
(
6–7
), pp.
539
543
.
16.
Yin
,
H. J.
,
Yang
,
Z.
,
Chen
,
A. Q.
, and
Zhang
,
N.
,
2012
, “
Experimental Research on a Novel Cold Storage Defrost Method Based on Air Bypass Circulation and Electric Heater
,”
Energy
,
37
(
1
), pp.
623
631
.
17.
Abdel-Wahed
,
R. M.
,
Hifni
,
M. A.
, and
Sherif
,
S. A.
,
1983
, “
Hot Water Defrosting of a Horizontal Flat Plate Cooling Surface
,”
Int. J. Refrig.
,
6
(
3
), pp.
152
154
.
18.
Krakow
,
K.
,
Lin
,
S.
, and
Yan
,
L.
,
1993
, “
An Idealized Model of Reversed Cycle Hot Gas Defrosting
,”
ASHRAE Trans.
,
99
(
2
), pp.
317
358
.
19.
Hoffenbecker
,
N.
,
Klein
,
S. A.
, and
Reindl
,
D. T.
,
2005
, “
Hot Gas Defrost Model Development and Validation
,”
Int. J. Refrig.
,
28
(
4
), pp.
605
615
.
20.
Payne
,
V.
, and
O'Neal
,
D. L.
,
1995
, “
Defrost Cycle Performance for an Airsource Heat Pump With a Scroll and a Reciprocating Compressor
,”
Int. J. Refrig.
,
18
(2), pp.
107
112
.
21.
Dong
,
J.
,
Jiang
,
Y.
,
Deng
,
S.
,
Yang
,
Y.
, and
Qu
,
M.
,
2012
, “
Improving Reverse Cycle Defrosting Performance of Air Source Heat Pumps Using Thermal Storage-Based Refrigerant Sub-Cooling Energy
,”
Building Service Eng.
,
33
(
33
), pp.
223
236
.
22.
Cui
,
J.
,
Li
,
W. Z.
,
Liu
,
Y.
, and
Jiang
,
Z. Y.
,
2011
, “
A New Time- and Space-Dependent Model for Predicting Frost Formation
,”
Appl. Therm. Eng.
,
31
(
4
), pp.
447
457
.
23.
Pineda
,
S. M.
,
Diaz
,
G.
,
2011
, “
Performance of an Adiabatic Cross-Flow Liquid-Desiccant Absorber Inside a Refrigerated Warehouse
,”
Int. J. Refrig.
,
34
(
1
), pp.
138
147
.
You do not currently have access to this content.