A study on the operational stability of a refrigeration system having a variable speed compressor

Chen, Yiming; Deng, Shiming; Xu, Xin; Chan, Ming Yin Jonathan

doi:10.1016/j.ijrefrig.2008.04.012

Cited by 42 publications

(18 citation statements)

References 15 publications

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“…Various studies have been conducted on twophased flow patterns of refrigerants. (Haverkamp et al 2006;Chinnov and Kabov 2006;Saisorn and Wongwises 2008;Shao et al 2009; Rebrov 2010; Awad and Muzychka 2014) However, this is not true regarding refrigerant-oil mixtures due to the difficulties found in its evaluation and experimentation. Nonetheless, the changes in flow pattern by the addition of oil can be explained through foaming.…”

Section: Effect Of the Lubricant Oil Mixture In The Superheated Regionmentioning

confidence: 99%

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A Review of the Effects of Changes in the Void Fraction of the Superheated Region on the Tev Operation and Evaporator Stability

Ramos

González

2016

RETERM

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A level of superheat is necessary to ensure proper operation of vapor- compression refrigeration systems. An overly superheated vapor prior to entering the compressor can render the system inefficient, while inadequate superheat can result in evaporator instability and compressor damage. The void fraction present in the suction line is directly related to evaporator stability and the hunting phenomenon in the thermostatic expansion valve (TEV). This article aims at reviewing superheated region-related researches in the field of refrigeration as they relate to the operation of the TEV and the stability of the evaporator. In a first part, literature review will explain the causes of the void fraction in the superheated region and the second part describes the effects of the lubricant oil on the void fraction. The third part of this article is a review of the effects of the superheated region on the TEV and on evaporator stability, explaining the causes of the hunting phenomena and evaporator instability.

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Section: Effect Of the Lubricant Oil Mixture In The Superheated Regionmentioning

confidence: 99%

“…Thus, extrapolating a MSS line from one system to another can result in lack of precision. (Chen et al 2008) At the time, the MSS theory was developed for single speed compressors. Varying compressor speed is known to reduce energy consumption in refrigeration systems and it is becoming widely used today.…”

Section: Evaporator Instabilitymentioning

confidence: 99%

A Review of the Effects of Changes in the Void Fraction of the Superheated Region on the Tev Operation and Evaporator Stability

Ramos

González

2016

RETERM

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“…To improve the energy saving of VCC system under different demands of cooling capacity, appropriate superheat set point based on the current demand of cooling load is determined [14]. The nonlinear relationship between stable superheat degree and cooling load in VCC systems is measured by curve fitting which indicated that when the cooling load is lower than a particular value, the superheat remains at a minimum value; similarly, when the cooling load is greater than a particular value, the superheat degree remains at a maximum value, shown in (5 …”

Section: B Dynamic Model Of Vapor Compression Refrigeration Cyclementioning

confidence: 99%

Energy-saving-oriented control strategy for vapor compression refrigeration cycle systems

Yin¹,

Li²,

Li³

et al. 2014

2014 9th IEEE Conference on Industrial Electronics and Applications

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Aiming at the disadvantage of system efficiency, a novel control strategy of maximizing energy saving while meeting the cooling demand for vapor compression refrigeration cycle (VCC) is presented. The VCC system is a core element in heating, ventilating, and air-conditioning (HVAC) system, and its coefficient of performance (COP), a measure of system efficiency for VCC system, is strongly influenced by the evaporator superheat and the pressure difference between evaporator and condenser, and the relationships between them are nonlinear thermodynamic coupling characteristics. In order to maximize the coefficient of performance (COP) which depends on operating conditions, in the meantime, meet the changing demands of cooling capacity, an analysis on the measured relationship between the setting value of stable superheat degree and cooling load is firstly carried out in this paper, then a model predictive control (MPC) based controller is developed for tracking the calculated setting curve of superheat and pressure difference based on model identified from experimental data. During the proposed control strategy, an optimization problem is solved which produces the maximal effect on the system performance. The effectiveness of the control performance is validated on the experimental rig.

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“…The cause of instability may be explained as the influence of the inherent characteristics of two-phase flow in evaporator and also the impact of the system control characteristics [6]. The former emphasizes particularly on the oscillations of two-phase flow of the refrigerant in evaporation process; its result is regarded as the basis of the system instability.…”

Section: Introductionmentioning

confidence: 99%

Two-phase flow instabilities in horizontal straight tube evaporator

Liang

Shao

Tian

et al. 2011

Applied Thermal Engineering

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Abstract:It is essential to ensure the stability of a refrigeration system if the oscillation in evaporation process is the primary cause for the whole system instability. This paper is concerned with an experimental investigation of two phase flow instabilities in a horizontal straight tube evaporator of a refrigeration system. The relationship between pressure drop and mass flow with constant heat flux and evaporation pressure is measured and determined. It is found that there is a negative slope section in the middle of positive slope pressure drop versus mass flow velocity thus making the velocity a multi-valued function of pressure drop.Three types of dynamic instabilities including the density wave instability, pressure drop instability and thermal instability are found under the conditions of heat flux from 5 to 17 kW/m 2 , mass velocity from 150 to 1500 kg/(m 2 ·s), and evaporating pressure from 0.5 to 0.8 MPa. The density wave oscillation occurs at almost all mass velocities; its period is about 1~3 seconds and its amplitude is the lowest. The pressure drop oscillation takes place in a negative slope section; its period is about 10 seconds. The thermal oscillation can be induced at a high mass flow velocity, and its period is of 60 seconds and the amplitude is the highest among the † Corresponding

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A study on the operational stability of a refrigeration system having a variable speed compressor

Cited by 42 publications

References 15 publications

A Review of the Effects of Changes in the Void Fraction of the Superheated Region on the Tev Operation and Evaporator Stability

A Review of the Effects of Changes in the Void Fraction of the Superheated Region on the Tev Operation and Evaporator Stability

Energy-saving-oriented control strategy for vapor compression refrigeration cycle systems

Two-phase flow instabilities in horizontal straight tube evaporator

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