Research and Development on a Packaged Split-Type Ice-Storage Air-Conditioning System

• Main Authors: Jwo, Ching-Song, 卓清松
• Other Authors: Sih-Li Chen
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/96072642450026998311

博士 === 國立臺灣大學 === 機械工程學系 === 85 === ABSTRACT The primary subject of this study is the research and development of a packaged split-type ice-storage air- conditioning system. This thesis consists of three major parts: development of the rating correlation for capillary tubes, establishment of the ice-storage process for a full storage ice- storage air-conditioning system, design of the prototype of a packaged split-type air-conditioner for a partial storage ice- storage air-conditioning system. First, a theoretical model for the flow of refrigerants through adiabatic capillary tubes which used in split-type air-conditioning system was developed. The flow of refrigerant in the capillary tube is characterized into a subcooled liquid region, a metastable liquid region, a metastable two-phase region, and an equilibrium two-phase region. The calculated results are compared well with the earlier R-22 experimental data. By incorporating with the theoretical predictions, a series of correlation for the design of R-134a flowing through adiabatic capillary tubes has also been developed. The ratings based on the curve fitting of capillary theory predictions include both the geometric and system operating factors. The proposed correlation, presented in the algebraic form, are quite simple and versatile. They can be used to calculate the mass flux and pressure drop directly from a given capillary tube selection. The optimal capillary size corresponding to any given set of system operating conditions can also be calculated. Calculation procedures are illustrated in examples to demonstrate the present rating methods by using the proposed correlation. These rating correlation are especially useful for system computer simulation, when the capillary tubes are served as metering devices. Next, a package ice-storage air-conditioning system for full storage is theoretically and experimentally investigated. The system consists a compressor, an air-cooled condenser, a thermostatic expansion valve and a direct-expansion coil plate evaporator for ice formation. Besides, a set of prototype experimental units with a capacity of 5 tons was designed. Data from the theoretical simulation proposed in this study show a good agreement with the experimental results. The results of the simulation analysis are used to explore different ice storage plate arrangements for the evaporation inside the ice-storage air-conditioning system in order to establish the optimum system configuration. Some design guidelines are also provided to serve as a reference for the design purpose. Finally, a packaged split-type air-conditioner prototype with partial ice-storage was designed and manufactured for applying the cold storage concept to residential and office spaces. This air-conditioner prototype can operate efficiently in combining the load need between traditional air-conditioning and ice-storage discharge. The optimal operation strategy corresponding to different load conditions is described and demonstrated. Satisfactory results of cold storage have been achieved concerning the consistency between the theoretical analysis and experimental results of an ice-storage subsystem.