Packaged Air Conditioners Research Articles

PAC용 양흡입 시로코홴의 공력성능에 관한 실험적 연구

Abstract ：The aerodynamic performance of double inlet sirocco fan is strongly dependent upon the design factors of impeller and scroll. In this paper, the change of scroll size was adopted to investigate the aerodynamic performances of double inlet sirocco fan and indoor PAC. Especially, a scroll expansion angle and a cut-off clearance ratio were considered to change the scroll size. In addition, the installation depth between double inlet sirocco fan and indoor PAC was considered. As a result, the total pressure efficiency of double inlet sirocco fan shows about 62%∼73% according to the change of scroll expansion angles. Moreover, the flowrate performance of indoor PAC is the best at the condition of a scroll expansion angle of 8°, an installation depth of 15 mm and a cut-off clearance ratio of 8%. Key Words ：Aerodynamic Performance, Cut-off Clearance Ratio, Double Inlet Sirocco Fan, Sirocco Impeller, Package Air-Conditioner, Scroll, Scroll Expansion Angle *†김장권(교신저자) : 군산대학교 동력기계시스템공학과E-mail : flowkim@kunsan.ac.kr, Tel : 063-469-1848** 오석형 : 군산대학교 기계공학부*†Jang-Kweon Kim(corresponding author) : Department of Power System Engineering, Kunsan National University.E-mail : flowkim@kunsan.ac.kr, Tel : 063-469-1848** Seok-Hyung Oh : School of Mechanical Engineering, Kunsan National University.

Advancing evaporative rooftop packaged air conditioning: A new design and performance model development

This paper presents a technological advancement in evaporative cooling rooftop air conditioning comprising a uniquely designed evaporative water cooler that includes a multi-stage hydronic unit and high thermal performance. In the new design, the water cooler is a counterflow air-to-air heat exchanger in which ambient air is pre-cooled in a dry path on one side of a heat transfer surface by water flowing on the other side of the surface. The water is then cooled by evaporation in a wet path by a secondary air stream flowing through the heat exchanger on the same side as the water but in the opposite direction. Outside air is cooled in the dry passages and then enters the wet passages at a lower wet bulb temperature than that of the outdoor air, potentially producing a lower sump water temperature compared to those produced by traditional evaporative condensers. We also developed a computer model to simulate the performance of the rooftop packaged unit. The model is based upon the Simulation Problem Analysis and Research Kernel (SPARK) simulation program and can be used to optimize component sizes and to perform an economic analysis. In addition, the model can be used for fault detection and diagnosis during operation. The simulation model was calibrated with experimental data obtained from the study and was then used for optimal sizing and performance tracking. ► Designed a hydronic rooftop packaged unit with significant efficiency improvement. ► The key advancement of the rooftop unit is the CEWC unit. ► The new rooftop unit can achieve a 25% reduction in overall annual energy use. ► The unit can achieve a 60% reduction in annual cooling energy use in dry climates. ► The simulation model could reasonably simulate the CEWC and the entire rooftop unit.

Development of Packaged Air Conditioners for Data Center with Outdoor Air Cooling (Analysis of Performance on Pump Cycle)

Development of Packaged Air Conditioners for Data Center with Outdoor Air Cooling (Analysis of Performance on Pump Cycle)

401 データセンタ向け外気冷房型空冷パッケージ空調機の開発 : ポンプサイクルにおける性能評価(省エネルギー(1))

401 データセンタ向け外気冷房型空冷パッケージ空調機の開発 : ポンプサイクルにおける性能評価(省エネルギー(1))

A Proposal of Cooling Capacity Estimation method for Onsite Performance Verification of Inverter-drive Packaged Air Conditioners

A Proposal of Cooling Capacity Estimation method for Onsite Performance Verification of Inverter-drive Packaged Air Conditioners

Fault Detection and Diagnostics for Commercial Coolers and Freezers

Most of the previous diagnostics research for vapor-compression equipment has been performed for packaged air conditioners and chillers. This paper describes application of a decoupling-based diagnostic technique that was originally developed for air conditioners to equipment used in walk-in coolers and freezers. Testing was performed on a small, restaurant-style walk-in cooler and a small walk-in freezer for faulted and unfaulted conditions. The data was then used to characterize how the fault features respond to faults and to evaluate the performance of the decoupling-based diagnostic technique.

신조 8,500GT 화학물 운반선의 여름철 선실 내 온열환경 실측평가

The purpose of this study is to measure and analyze the indoor thermal conditions of a 8,500GT class chemical carrier which was launched on July 2007. The measurement was operated from 4th June to 4th June 2007, just before handing over to Owner. Followings are the results of this study. (1)The temperature variations of supply air were related to the outdoor temperature variations, but the humidity was stable at . (2)The temperature variations at the representative position of bridge, restaurant, crew`s cabin showed gentle slopes. but that of conference room was very steepy. The humidities of bridge and restaurant were unstable because of outdoor-contact and cooking, respectively. (4)The temperature and humidity of ECR(Engine Control Room) which was designed to supply heating and cooling by PAC(Package Air Conditioner) were directly affected by the operating conditions of PAC. (5)The measured supply air volume from dampers of bridge, crew`s cabin and conference room were satisfied with the design supply air volume. (5)For the improvement of the indoor thermal conditions, the temperature of crew`s cabin and restaurant and the humidity of conference room, and the temperature and humidity of bridge should be controlled, respectively.

STUDY ON REDUNDANT CONFIGURATIONS OF AIR-CONDITIONER AND COOLING TOWER

Water-cooled packaged air conditioner systems are gaining renewed recognition from the perspective of preventing the urban heat island phenomenon. Up to now, however, there have been no reliable methods for optimizing equipment capacity. For this reason, in telecommunications buildings, which demand high levels of reliability, there are cases of excessively redundant configurations, which not only result in reduced space efficiency, but also invite reduced operating efficiency due to partial load operations. In a previous report, we constructed a model for evaluating water-cooled packaged air conditioner systems, and demonstrated that it was possible to study equipment configurations based on these reliability evaluations. In this report, using this reliability evaluation model, we showed the equipment configurations required for each level of reliability. Furthermore, we proposed a design process using the reliability evaluation methods in this research, taking into account reduced capacity of the cooling tower resulting from the passage of time.

The impact of evaporator fouling and filtration on the performance of packaged air conditioners

The goal of the study presented in this paper was to evaluate the impact of different filter types on the performance of three typical packaged air conditioners under both clean and fouled conditions. In a companion paper, combinations of six different levels of filtration and four different coils were tested under clean and fouled conditions. From the tests, it was found that fouling has a relatively small impact on air-side effective heat transfer coefficient, but can have a large impact on coil pressure drop. Data from the experimental study were used in developing simulation models for the three packaged air conditioners. Simulations show that the equipment cooling capacity is reduced with fouling primarily because of a decrease in air flow due to the increased pressure drop. In most cases, EER (energy efficiency ratio) was reduced with fouling primarily due to increased fan power. However, the changes in EER were relatively small, in the range of 1–10%. Equipment having low efficiency filters had higher EER after fouling than equipment with high efficiency filters, because high efficiency filters result in significantly higher pressure drops than low efficiency filters. The impact of the evaporator side fan efficiency was found to be significant. The energy penalty associated with high efficiency filters was reduced greatly when fan efficiency increased. Although high efficiency filters cause higher energy penalties they provide considerably better air quality. The quantity of dust passing through the coil with an MERV14 filter was approximately 30 times less than the dust passing the coil with an MERV4 filter. This difference was doubled when the MERV14 filter was compared to a case with no filter in place.

THERMAL PERFORMANCE EVALUATION OF ROOM AIR CONDITIONERS EVAPORATORS

This work presents a thermal performance evaluation of a fin-and-tube evaporator - that is widely used in packaged air conditioning equipment - using a balanced calorimeter developed to simulate similar running conditions. The calorimeter determines the heat rate absorbed by the evaporator, providing qualitative analysis of performance for a given geometry. The calorimeter inside air is dried out due to the condensation process on the evaporator under test during the transient period. By this way it is possible to preview the humidity of the calorimeter domain and its influence with the instrumentation measurement. The heat transfer rate absorbed by the evaporator is obtained by a lumped approach using the energy conservation that is applied to the calorimeter domain, and is taken on the boundaries of the equipment. Physical parameters such as overall heat transfer coefficient for several types of fins can then be predicted in order to provide information for improving the energy-efficiency-oriented design. The uncertainties are estimated by the propagation of relative effects. Uncertainties are evaluated taking into account the systematic effects. Results are shown in terms of evaporator overall heat transfer coefficient and heat transfer rate as a function of inlet air temperature.

Development and Evaluation of a Night Ventilation Precooling Algorithm

This paper describes the development and evaluation of a simple algorithm for night ventilation precooling that can be integrated at low cost within a controller for packaged air conditioners that employ economizers, such as rooftop units. In addition to reducing operating costs, the algorithm ensures that indoor comfort is maintained. The basic night ventilation precooling algorithm was developed based upon a simple optimization and heuristics derived from simulation results. The cost savings potential of the algorithm was evaluated using simulations for a range of buildings and climates throughout California. The buildings were representative of small commercial buildings that employ packaged air-conditioning equipment with integrated economizers. The annual savings in compressor energy for night ventilation ranged from about 0 to 53% depending on the location and building type. The savings in total air-conditioning electrical energy usage are much smaller than the compressor savings due to an increase in fan energy. The annual electrical energy savings varied between about 0 and 8%. The electrical demand cost savings associated with night ventilation varied between about 0 and 28%, whereas the total annual electrical cost savings ranged from about 0 to 17%. The greatest percent savings occurred in cooler coastal climates having smaller total loads but significant opportunities for night ventilation precooling.

THERMAL PERFORMANCE EVALUATION OF ROOM AIR CONDITIONERS EVAPORATORS

This work presents a thermal performance evaluation of a fin-and-tube evaporator - that is
widely used in packaged air conditioning equipment - using a balanced calorimeter
developed to simulate similar running conditions. The calorimeter determines the heat
rate absorbed by the evaporator, providing qualitative analysis of performance for a given
geometry. The calorimeter inside air is dried out due to the condensation process on the
evaporator under test during the transient period. By this way it is possible to preview the
humidity of the calorimeter domain and its influence with the instrumentation measurement.
The heat transfer rate absorbed by the evaporator is obtained by a lumped approach using
the energy conservation that is applied to the calorimeter domain, and is taken on the
boundaries of the equipment. Physical parameters such as overall heat transfer coefficient
for several types of fins can then be predicted in order to provide information for improving
the energy-efficiency-oriented design. The uncertainties are estimated by the propagation
of relative effects. Uncertainties are evaluated taking into account the systematic effects.
Results are shown in terms of evaporator overall heat transfer coefficient and heat transfer
rate as a function of inlet air temperature.

冷却水系統を考慮した年間冷房型水冷パッケージ空調システムの効率向上に関する研究

In this research we will propose an operational method for improving the efficiency of water-cooled packaged air conditioning systems. Water-cooled packaged air conditioners are installed at large-scale communication facilities and data centers. In the past, efforts were made to improve the efficiency of air-cooled packaged air conditioners using technologies that operated the air conditioners in low compression ration regions. By applying these technologies to water-cooled packaged air conditioners, we have succeeded in improving the efficiency of the refrigeration cycle. It is still necessary, however, to reduce the power consumption of the cooling tower and cooling pump in order to improve the efficiency of the air conditioning system as a whole. In this paper, we conducted system simulations, and calculated efficiency over one year. Based on the results of these simulations, we expect to be able to improve efficiency by about 10% at 30% partial load by minimizing the repetition of start/stop operations in the cooling tower.

Automated Fault Detection and Diagnostics for Vapor Compression Cooling Equipment

This paper provides an overview of research related to automated fault detection and diagnosis for chillers, packaged air conditioners, and other vapor compression cooling equipment. The paper discusses the benefits, constraints, and possible products for FDD applied in the HVAC&R industry, presents results of fault surveys for packaged air conditioners and chillers, outlines the general structure and elements of an FDD system for HVAC&R equipment, describes specific methods associated with different FDD elements, and presents results from some specific case studies. The paper also attempts to provide an assessment of the state-of-the-art in FDD for vapor compression equipment and to identify the steps necessary to achieve widespread application.

The Latest Trend of Energy-Saving Package Air Conditioners

The Latest Trend of Energy-Saving Package Air Conditioners

403 氷蓄熱式パッケージエアコンの省エネルギー性評価

403 氷蓄熱式パッケージエアコンの省エネルギー性評価

430 間接外気冷房機能を付加した年間冷房型パッケージ空調機の効率向上に関する研究 : その3 実負荷環境下での性能試験結果(省エネルギー(I))(空気調和・冷凍技術)

This paper study on year-round cooling type packaged air conditioner by incorporating a refrigerant pump. When outdoor air temperature is low, the efficiency of year-round cooling type air conditioner can be improved by circulating refrigerant by the refrigerant pump. This paper discusses field trial results and calculates energy saving effects based on cooling capacity and electrical consumption at field trial. As a consequence result, this air conditioner can save more than 50% electrical energy at Sapporo and more than 40% at Tokyo in comparison with ordinary air conditioner.

Study on Efficiency Improvement of Packaged Air Conditioners for Year Round Cooling with Indirect Outdoor Air Cooling. Study on Control Methods of Room Air Temperature and Superheat.

The air conditioner which cools telecommunication equipment rooms or computer rooms must operate throughout the year. So we apply refrigerant pump cycle to the air conditioner to improve coefficient of performance (COP) at low outdoor air temperature. At first, this paper discusses two kinds of control methods. One is superheat control to manipulate refrigerant pump frequency. Refrigerant pump cycle controlled by this method can operate higher efficiency than that controlled by expansion valve. The other is room air temperature control method to manipulate air flow rate = of condenser. Next, this paper discusses year round electric consumption comparison with conventional air conditioner. The electric consumption of the air conditioner with refrigerant pump is 50% shorter than that of conventional air conditioner.

躯体の熱容量を利用した動的最適化空調運転がエネルギー消費特性に及ぼす影響について

Thermal capacity of building envelope has an effect of reducing heating and cooling storage load. This paper argues how much peak and cumulative energy can be reduced by utilizing building thermal storage. The author has already proposed a dynamic optimization technique solving such a problem. In this paper, the optimization technique is employed for annual calculation where the object system is an office room equipped with electric-driven packaged air conditioner. The optimized functions are 1) cumulative electricity, 2) peak electricity, and 3) electricity charge. Electricity charge optimization is dealt with as multi-objective problem composed of minimizing cumulative electricity and minimizing peak electricity. The optimal trajectory of room air temperature and electrical demand are also investigated for each season.

Theoretical Performance Comparison of CO2 Transcritical Cycle Technology Versus HCFC-22 Technology for a Military Packaged Air Conditioner Application

The world-wide agreement to restrict the use of chlorofluorocarbons (CFCs) and hydrofluorocarbons has prompted research into the possibilities of replacement refrigerants, particularly those occurring naturally in the environment. One such natural refrigerant, carbon dioxide, has been considered for certain refrigeration and air conditioning applications. In order to evaluate the potential performance of a refrigeration cycle based on carbon dioxide, a cycle model has been developed which can simulate the operation of a carbon dioxide based refrigerator/air conditioner. This model is called ACCO2 and accounts for the realistic effects of the thermo-physical properties of carbon dioxide. The model simulates the operation of a carbon dioxide based air conditioner that uses air as the heat source and heat sink. A parametric study has been conducted using ACCO2 as well as a validated cycle model which simulates the operation of an HCFC-22 based packaged air conditioner designed for use by the U.S. Army in a combat environment. The size and weight constraints of this application render HCFC-22 based units less efficient than typical HCFC-22 unitary air conditioners of the same capacity. It is hypothesized that these same constraints will not affect the performance of a carbon dioxide based packaged air conditioner as severely. The evaporative capacity, compressor power, and COP were calculated for each cycle over a range of indoor and outdoor temperatures, and used as a basis for comparing the two cycles.