Control strategy of compressor and sub-cooler in variable refrigerant flow air conditioning system for high EER and comfortable indoor environment

Tu, Qiu; Zhang, Lina; Cai, Wei; Guo, Xuerang; Yuan, Xiaojun; Deng, Chenmian; Zhang, Jie

doi:10.1016/j.applthermaleng.2018.05.118

Cited by 34 publications

(21 citation statements)

References 32 publications

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“…Compressor speed has an impact on refrigerant flow rate in the cycle; consequently, it would affect the refrigeration capacity. EEV is also working as the main part of variable speed refrigeration systems to regulate degree of refrigerant superheat at desired values and to maintain pressure ratio at optimum working levels [10]. System performance under manual operation was examined to determine the effect of compressor speed and valve opening at constant inlet water temperatures to the evaporator and condenser 17 and 29 °C, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…The experimental results showed that energy saving can be increased by 38.9% using a variable speed driver for both the compressor and fans compared to single speed equipment. Tu et al [10] developed a dynamic model to control a variable refrigerant flow system including variable speed compressor, EEV and sub-cooler. The optimum energy efficiency ratio was at narrow EEV opening under partload condition.…”

Section: Introductionmentioning

confidence: 99%

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Effects of compressor speed and electronic expansion valve opening on the performance of R410a water chiller system

Al-Hassani

Al-Badri

2020

ejuow

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Refrigeration and air conditioning systems consume high rates of electrical energy of the total global power consumption. The major part of this energy is used by compressor which is the main equipment in vapor compression refrigeration systems. In this study, the performance of a variable speed chilled water refrigeration system with electronic expansion valve (EEV) is experimentally investigated. The system is composed of variable speed rotary compressor, water cooled condenser, electronic expansion valve, and evaporator with refrigerant R410a for one tone cooling capacity. The results showed that the EEV opening was related to the compressor speed at limits of refrigerant subcool and system stability to achieve better performance. Refrigerant superheats increased with closing the EEV at constant compressor speed. Moreover, the degree of superheat was inversely proportional to the compressor speed at constant EEV opening. The coefficient of performance (COP) was improved by about 2.2 to 4.0% by controlling the EEV at constant compressor speed. Increasing compressor speed from 1200 to 3600 rpm resulted in decreasing system COP from 5.2 to 2.35 due to the increase of the power consumed by compressor.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of compressor speed and electronic expansion valve opening on the performance of R410a water chiller system

Al-Hassani

Al-Badri

2020

ejuow

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“…These types of HPs can adjust their heating capacity to the heat load by continuously regulating their compressor speed by means of pulse width modulation (PWM) and pulse amplitude modulation (PAM) via the inverter. Shao [7] showed that the proper modulation of the capacity to the heat demand significantly reduces the power consumption of the HP, thus the compressor operating speed is essentially affecting the performance of the HP [8]. Several studies confirmed the influence of the compressor speed on the capacity and thus control strategies via frequency adjustment of the compressor have been developed [9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Fixing Efficiency Values by Unfixing Compressor Speed: Dynamic Test Method for Heat Pumps

et al. 2019

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The growing market penetration of heat pumps indicates the need for a performance test method that better reflects the dynamic behavior of heat pumps. In this contribution, we developed and implemented a dynamic test method for the evaluation of the seasonal performance of heat pumps by means of laboratory testing. Current standards force the heat pump control inactive by fixing the compressor speed. In contrast, during dynamic testing, the compressor runs unfixed while the heat pump is subjected to a temperature profile. The profile consists of the different outdoor temperatures of a typical heating season based on the average European climate and also includes temperature changes to reflect the dynamic behavior of the heat pump. The seasonal performance can be directly obtained from the measured heating energy and electricity consumption making subsequent data interpolation and recalculation with correction factors obsolete. The method delivers results with high precision and high reproducibility and could be an appropriate method for a fair rating of heat pumps.

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“…Shao [7] showed that the proper modulation of the capacity to the heat demand significantly reduces the power consumption of the HP; thus the compressor operating speed is essentially affecting the performance of the HP [8]. Several studies confirmed the influence of the compressor speed on the capacity and thus control strategies via frequency adjustment of the compressor have been developed [9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Fixing Efficiency Values by Unfixing Compressor Speed: Dynamic Test Method for Heat Pumps

Palkowski¹,

Zöttl²,

Malenkovic³

et al. 2019

Preprint

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The growing market penetration of heat pumps indicates the need for a performance test method which better reflects the dynamic behavior of heat pumps. In this contribution, we developed and implemented a dynamic test method for the evaluation of the seasonal performance of heat pumps by means of laboratory testing. Current standards force the heat pump control inactive by fixing the compressor speed. In contrast, during dynamic testing, the compressor runs unfixed while the heat pump is subjected to a temperature profile. The profile consists of the different outdoor temperatures of a typical heating season based on the average European climate and also includes temperature changes to reflect the dynamic behavior of the heat pump. The seasonal performance can be directly obtained from the measured heating energy and electricity consumption making subsequent data interpolation and recalculation with correction factors obsolete. The method delivers results with high precision and high reproducibility and could be an appropriate method for a fair rating of heat pumps.

show abstract

Control strategy of compressor and sub-cooler in variable refrigerant flow air conditioning system for high EER and comfortable indoor environment

Cited by 34 publications

References 32 publications

Effects of compressor speed and electronic expansion valve opening on the performance of R410a water chiller system

Effects of compressor speed and electronic expansion valve opening on the performance of R410a water chiller system

Fixing Efficiency Values by Unfixing Compressor Speed: Dynamic Test Method for Heat Pumps

Fixing Efficiency Values by Unfixing Compressor Speed: Dynamic Test Method for Heat Pumps

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