“Performance Representation of Variable-speed Compressor for Inverter Air Conditioners Based on Experimental Data
Department of Building Science, Tsinghua University, Beijing, 100084, China International Journal of Refrigeration
(Impact Factor: 2.24).
12/2004; 27(8):805-815. DOI: 10.1016/j.ijrefrig.2004.02.008
Variable speed control of compressors is one of the best methods to regulate the capacity of heat pumps and air conditioners. An analysis is conducted for modeling the variable speed compressor for simulation of inverter air conditioner and heat pump. Having scattered the real operation performance of inverter compressor into infinite operation performance of constant speed compressor, the map-based method is utilized to fit the performance curves of inverter compressor. The model is built at the basic frequency and the map condition as the second-order function of condensation temperature and evaporation temperature. Then it is corrected by the compressor frequency as the second-order function of frequency and by the actual operating condition as the actual specific volume of the suction gas. This method is used to set up simulation models of three different compressors. Compared with the data provided by the compressor manufacturers, the average relative errors are less than 2, 3 and 4% for refrigerant mass flow rate, compressor power input and coefficient of performance (COP), respectively. This model of variable speed compressor is suitable for the simulation of inverter air conditioner and heat pump systems. Based on the experimental data and simulation model, the frequency at zero mass flow rate and power input at zero frequency are discussed and the relation between COP and compressor frequency is analyzed.
Available from: Kyung Chun Kim
- "In their test, the compressor operated across a wide range, from 1100 to 9000 rpm. Shao et al. (2004) determined the performance of a variable speed compressor for inverter air conditioners. Based on their experimental data and simulation model, the frequency at zero mass flow rate and the power input at zero frequency are discussed, and the relation between COP and compressor frequency was analyzed. "
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ABSTRACT: The capacity and efficiency of a capacity modulation compressor based on a two-stage rotary compressor are studied experimentally. The test results are compared with results from a numerical analysis (Part Ι). The proposed compressor has superior performance and efficiency compared to the conventional bypass-type single-stage compressor. The results satisfy a maximum 3% error requirement for all air conditioning operational conditions. Our results show that for the power mode, the cooling capacity (1% higher than that of the bypass-type) and power consumption (3% lower than that of the bypass-type) of the two-stage rotary compressor are slightly improved. For the saving mode, the cooling capacity (10% higher than that of the bypass-type) and power consumption (8% lower than the bypass-type) are significantly improved. In addition, the results of a loss analysis based on the pressure-volume (P-V) diagram exactly matched the results of the numerical simulation.
Available from: Xianting Li
- "Therefore , two independent containers with a large volume are connected to Port E and Port C of the valve in the simplified physical model (shown in Fig. 4). The compressor model is established according to the results from Shao  on the basis of the compressor real performance data provided by the manufacturer. It is assumed that the compressor takes 5 s to reach the rated frequency. "
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ABSTRACT: A hybrid air conditioner combining a thermosyphon cycle with a vapor compression refrigeration cycle has a large energy saving potential compared with a common air conditioner for spaces requiring year-round cooling. The performance of the switch between the vapor compression mode and the thermosyphon mode largely impacts the safety and reliability of hybrid air conditioners. Therefore, a self-operated three-way valve is proposed. A thermodynamic model and a kinetic model are developed in this paper to evaluate the dynamic performance of the switch valve. The effects of the spring force constant, compressor discharging volume, fit clearance and piston length on the dynamic performance of the switch valve are analyzed. In conclusion, the proposed self-operated three-way valve can realize the switch operation accurately.
Available from: ijlct.oxfordjournals.org
- "Majority of studies conducted on heat pumps study have investigated the potential for efficiency improvement and capacity adjustment through the improvements in the major components of heat pumps, namely compressors, evaporators, condensers, expansion valves, heat exchangers and working fluid mixtures. They include Aynur et al. , Radermacher , Aprea et al. , McLinden and Radermacher , Nguyen , Hewitt and Huang , Hewitt et al. , Hewitt and McMullan , Pourreza-Djourshari and Radermacher , Zhiyi et al. , Feng et al. , Jeong-Gun et al. , Zhao et al. , Fu et al. , Shao et al. , Ma and Li , Duprez et al. , Noguchi et al. , Rosiek and Batlles , Ma and Zhao  and Chaturvedi et al. . The need for energy storage to take advantage of off-peak electricity (heating and cooling) systems has been acknowledged by many authors. "
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ABSTRACT: This paper reports on an experimental energy storage system, consisting of a longitudinally finned concentric container incorporating
98 kg of RT58 phase change material (PCM) with a melting point of 60°C. The research forms part of a wider study to explore
PCMs to take advantage of off-peak electricity tariffs. The experimental study results have been reported using temperature
time curves, isotherm plots, trend of heat transfer coefficients based on quantitative amounts of energy charged and discharged
from the PCM. Isotherm plots indicated uneven heat distribution and the charge and discharge rates of energy averaged 0.6
and 0.2 kW, respectively, prompting the need to develop a more efficient heat transfer technique to improve charge and discharge
rates. Increased average inlet heat transfer fluid temperature from 60.9 to 65.9°C improved heat transfer coefficient by as
much as 70% for charging and 11.3% for discharge process.
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