Condenser Fan Research Articles

Model-Based Condenser Fan Speed Optimization of Vapor Compression Systems

Vapor compression systems (VCS) cover a wide range of applications and consume large amounts of energy. In this context, previous research identified the optimization of the condenser fans speed as a promising measure to improve the energy efficiency of VCS. The present paper introduces a steady-state modeling approach of an air-cooled VCS to predict the ideal condenser fan speed. The model consists of a hybrid characterization of the main components of a VCS and the optimization problem is formulated as minimizing the total energy consumption by respectively adjusting the condenser fan and compressor speed. In contrast to optimization strategies found in the literature, the proposed model does not relay on algorithms, but provides a single optimization term to predict the ideal fan speed. A detailed experimental validation demonstrates the feasibility of the model approach and further suggests that the ideal condenser fan speed can be calculated with sufficient precision, assuming constant evaporating pressure, compressor efficiency, subcooling, and superheating, respectively. In addition, a control strategy based on the developed model is presented, which is able to drive the VCS to its optimal operation. Therefore, the study provides a crucial input for set-point optimization and steady-state modeling of air-cooled vapor compression systems.

Performance Evaluation of Axial Flow Wind Turbine Integrated with The Condenser

This study investigated the application of an axial flow wind turbine integrated with a condenser. The exhaust air from condenser was used to drive the wind turbine by a ducted turbine system. There were two parameters varied in this work: the blade number and the blade pitch angle. The blade number used was two blades, five blades, and ten blades, while the blade pitch angles were 5°, 10°, 15°, 20°, 30°, and 45°. The diameter of the wind turbine was 495 mm. The model of the condenser had a fan diameter of 600 mm and the range of the average air velocity of 2.01 m/s - 7.86 m/s. The maximum mechanical power was 10.72 W for air velocity of 7.86 m/s. The maximum power coefficient recorded was 0.38 for the tip speed ratio of 1.3 on the blade number of five blades and a pitch angle of 10°. The maximum exhaust air energy recovery was 13.64% of the power consumption of the condenser fan.

A comparative experimental study on the performance of the air‐conditioning system through effective condenser cooling and preheating the refrigerant

AbstractA comparative study was made on air conditioning system performance improvement by effective condenser cooling and preheating the refrigerant. This study was described with the experimental investigation through a test rig fabricated from car air conditioning components. In which slight modifications were made such as compressor has to run by the electric motor with provision to measure power consumption during functioning and condenser fan has to replace with exhaust fan enclosed by the cooling pad in which water is supplied with a controlled flow rate using a water pump. Preheating of refrigerant is done using engine exhaust gas with counterflow heat exchanger setup. Air conditioning test rig was run to achieve the desired cooling effect for two processes. The coefficient of performance (COP) was calculated in both operating conditions for the same cooling effect and comparative study was made. The conclusion revealed that a new cooling method showed higher COP than preheating. By this approach, the percentage increase in heat removal rate up 37% was achieved which results in decreases the compressor running time thus mileage of vehicle can be improved significantly.

Dynamic performance analysis of inverter-driven split air conditioner

Abstract Variable speed technology has a great potential for improving energy efficiency and performance of vapor compression refrigeration cycle. Therefore, the study of dynamic characteristics of the refrigeration cycle using this new technology becomes essential. This study experimentally investigates the dynamic behavior of a split R-410A air conditioner comprising variable speed compressor, variable speed condenser fan, three speed evaporator fan and electronic expansion valve. The characteristics of the conditioner have been presented during the startup and shutdown periods. Furthermore, the effect of changing evaporator fan speed during the running of the conditioner has been illustrated and discussed. The influence of evaporator and condenser inlet air temperatures on the power consumption and coefficient of performance of the conditioner has also been investigated. The experimental results show that increasing the condenser entering air temperature by 7 °C, the power consumption has been increased by 18% and the coefficient of performance decreased by 15%.

Performance Enhancement of an Air-Conditioning System using a Passive Add-on Device

Abstract Performance measurements of an air-conditioning system was performed with and without a Passive Add-on Device installed on top of its condenser unit. This device has a cylindrical shape with fixed radial blades, combining characteristics that streamline the flow, while changing its rotational speed. In addition to the thermodynamic measurements, the flow velocity distributions at the outlet of the condenser fan unit (no Add-on Device case) as well as at the outlet of the Add-on Device were both measured using hot-wire anemometry. The Add-on Device increased flow rotation as well as uniformity of axial velocity, while reducing the radial velocity component. By streamlining the flow, the Add-on Device led to enhancements by 5.4 % in terms of overall coefficient of performance of the tested air-conditioning unit, within the range of tests conducted in the present work.

Off-Design Performances of an Organic Rankine Cycle for Waste Heat Recovery from Gas Turbines

This paper presents an off-design analysis of a gas turbine Organic Rankine Cycle (ORC) combined cycle. Combustion turbine performances are significantly affected by fluctuations in ambient conditions, leading to relevant variations in the exhaust gases’ mass flow rate and temperature. The effects of the variation of ambient air temperature have been considered in the simulation of the topper cycle and of the condenser in the bottomer one. Analyses have been performed for different working fluids (toluene, benzene and cyclopentane) and control systems have been introduced on critical parameters, such as oil temperature and air mass flow rate at the condenser fan. Results have highlighted similar power outputs for cycles based on benzene and toluene, while differences as high as 34% have been found for cyclopentane. The power output trend with ambient temperature has been found to be influenced by slope discontinuities in gas turbine exhaust mass flow rate and temperature and by the upper limit imposed on the air mass flow rate at the condenser as well, suggesting the importance of a correct sizing of the component in the design phase. Overall, benzene-based cycle power output has been found to vary between 4518 kW and 3346 kW in the ambient air temperature range considered.

Numerical investigation of CSP air cooled condenser fan

Numerical investigation of CSP air cooled condenser fan

Management of Condenser Fan Speed and its Influence on the Split Air Conditioner Performance

Energy saving is the challenge of decreasing the quantity of energy consumption needed. This can be done by employing reliable and smart control system. In this article, an experimental study has been carried out to investigate the performance of a split air conditioning unit having a variable speed condenser fan. The rate of heat rejection airflow has been controlled according to the outdoor air temperature via a Proportional Integral Differential (PID) controller. The control algorithm allows increasing the condenser fan speed with the increase of outdoor air temperature and vice verse. The maximum rate of air flow of the fan is 0.43 m3/s at 42ºC outdoor air temperature and the minimum flow is 0.28m3/s. To facilitate variation of refrigerant flow rate according to the evaporator load, the traditional capillary tube was replaced with a suitable thermostatic expansion valve and liquid refrigerant reserve. The influence of condenser airflow modulation and its temperature on the air conditioner performance and also on the compressor power consumption has been investigated and presented at different evaporator loads. It has been found that a 10 % reduction in compressor power is achieved by increasing the condenser air flow by about 50%.

Experimental investigation of the effect of perimeter windscreens on air-cooled condenser fan performance

Perimeter windscreens are finding application in large air-cooled condensers (ACCs) as a mechanism to mitigate the negative effects of wind on ACC fan performance and dynamic blade loading. The limited literature specific to perimeter windscreens is inconsistent and the mechanisms by which these screens impact fan behaviour are not well understood. This study investigates the influence of perimeter windscreens on ACC fan volumetric effectiveness under windy conditions using a laboratory based experimental apparatus consisting of a scaled fan row consisting of three fans in the wind direction. Three different porous windscreen materials (differing solidity) were investigated along with the effect of varying windscreen height. A controllable cross-flow (wind) was achieved by connecting the apparatus to a low speed wind tunnel. Fan volumetric flow rate and shaft power were measured and flow visualization was achieved by means of particle imagery velocimetry to provide insight into the reasons for the observed fan behaviour. The apparatus corresponds to a full-scale ACC for which data relating to perimeter windscreen effects was available in the literature. A good correlation to these full-scale measurements was achieved giving confidence in the validity of the results of this study.Perimeter windscreens were observed to degrade edge fan volumetric effectiveness under windy conditions relative to the no-screen case in almost all cases considered in this study although evidence of a recovery of volumetric effectiveness was observed at high cross-flow (β = 0.36) for the case where a low solidity screen (α = 0.5) was installed across half or more of the platform inlet (L ≥ 0.5). An improvement in cooling effectiveness of up to 30% was observed relative to the no-screen case for the aforementioned screen configurations indicating that such perimeter windscreens may benefit the effective cost of cooling in ACCs under high wind conditions. The PIV flow visualization identifies deflection of the flow past the edge fan as the reason for the reduction in fan volumetric effectiveness when screens are installed. The negative impact of this deflection is counteracted by permeation of flow through the screen and into the edge fan when a low solidity screen covers a large portion of the platform inlet.It can therefore be concluded that, for the low platform ACC simulated in this study, perimeter windscreens are detrimental to ACC performance except at very high wind speeds. Use of low solidity retractable screens that can be deployed under high wind conditions (taking into account structural limitations) may have merit. This works extends the understanding of perimeter windscreen effects on ACC fans by investigating the effect of screen solidity and height in a controllable and validated experimental facility. It provides insight into the mechanisms through which perimeter screens influence ACC fans that can be used to further develop and improve the potential benefits of these screens.

Pengaruh Diameter dan Kecepatan Kipas Kondensor terhadap Suhu AC Mobil

The efficiency of the Air Conditioning (AC) system in a car depends on the process of compression, condensation, and evaporation. The new thought that arises is what if the diameter of the condenser fan blade is varied? The objectives of this study are: (1) to test the effect of the diameter of the condenser fan blade on AC temperature, and (2) to test the effect of condenser fan rotation speed on AC temperature. This research is using an experimental method. The results showed: 1) there was an effect of the diameter of the condenser fan on AC temperature, which was 16.7%; and 2) there is an influence of condenser fan rotation speed on AC temperature that is equal to 20.5%. These findings become a reference that to improve the performance of the AC, it can be done by increasing the heat transfer process in the condenser.

Improving the performance of the condenser fan in a subway train against the effects of crosswind flow by placing barriers

In this paper, the effect of crosswind flow and barrier placement on the performance of the condenser fan in a subway train is investigated. In addition, the amount of heat transfer on the condenser tubes is also analyzed. At different velocities of the train, variations in the velocity profile and drag force are determined for various geometries including triangular, rectangular, symmetric triangular barriers, and a barrier with parallel lines outside of the fan. Navier–Stokes, energy equations, and k– ω turbulence model have been used for the numerical modeling of the turbulent and incompressible flow. The results show that due to the created vortices behind the triangular and rectangular barriers, a negative velocity on the outflow of the fan is observed. Also, the symmetric triangular barrier minimizes the rotational flow on the top of the fan, and parallel paths have the most impact on the improvement of the fan's performance due to the elimination of all rotating flows. Finally, variations in temperature on the condenser tubes in the presence of barriers that are placed in the middle gap between the holes on the top of the condenser tubes are determined. These barriers move the crosswind flow toward the condenser tubes and decrease the output air temperature of the condenser.

Energy saving and environmental impact of optimizing the number of condenser fans in centrifugal chillers under partial load operation

In this paper, an optimization model is extended to optimize the coefficient of performance of refrigeration systems at partial load operation, based on optimal number of condenser fans. The sizes of vapor compression chillers are 703, 1266 and 1758 kW, and the number of fans varies from 1 to 6 while the ambient temperature ranges from 30 to 50 °C and partial load ranges from 0.25 to 1. Results show that the partial load where the optimized COP reaches its maximum value, ranges from 0.68 to 0.76 and decreases by increasing the size of chiller A correlation is proposed for partial load at which COP reaches its maximum value, as a function of nominal cooling capacity and outdoor ambient temperature. Finally, it is found that the average amount of 5.6 GWh/year electric energy saving and 5.1 ton/year CO2 emission reduction can be achieved by optimization of number of condenser fans.

The Thermal Analysis of a Semi-Open Heat Pump Drying System: An Experimental Investigation

One of the key advantages of heat pump (HP) systems is their ability to recover waste heat energy for useful input. In this study, the thermal performance of a heat pump drying system that recovers heat energy from the hot and moist exhaust air from the dryer was designed, constructed, and examined. The performance of this semiopen air source heat pump system was investigated and analysed by varying the refrigerant charge, the condenser fan speed, and the thermal expansion valve orifice size at ambient temperatures ranging from 23 – 26 C. The results indicated that by increasing the charge in the system, the refrigerant mass flow rate, heating capacity and coefficient of performance (COP) of the system increased to a certain maximum point before maximum charging. By increasing the refrigerant charge, both evaporation and condensation pressures of the system increased with condensation pressure indicating more sensitivity on the charge amount before optimum charging than evaporating pressure. The increase in refrigerant charge was observed to decrease the degree of superheat but increase the sub-cooling degree. At an optimum charge, the heating capacity for thermal expansion valve (TEV) of 0.3 mm diameter orifice is 15% greater than that of 0.2 mm diameter orifice. A system power consumption for O0.3 mm orifice was 3% greater than that of O0.2 mm orifice at the optimum charge amount. However, the COP of O0.3 mm orifice was 18% greater than that of O0.2 mm orifice.

Supermarket system characteristics and operating faults (RP-1615)

Supermarkets undergo various types of operating faults that can require costly preventive maintenance, service, and repairs. Because supermarkets are growing in number and in the variety of system types and characteristics, information about common faults and equipment is essential prior to investing effort on the development of new fault detection and diagnostics (FDD) methods or other improvements to system design and operation. A study was conducted to investigate supermarket equipment characteristics, such as the prevalence of central vs. distributed systems, condenser types, control strategies, and common operating faults such as refrigerant leakage, failed evaporator or condenser fans, failed compressors, etc. The data come from four sources: expert surveys, facility management system messages, service calls, and service records. Some of the results of the study are that centralized direct expansion systems with on/off compressor capacity control strategy and air-cooled condensers are the most common system types and refrigerant charge problems are the most common source of equipment failure. Case-related problems, in aggregate, are the most frequently occurring faults in supermarkets.

Energy performance evaluation of variable-speed packaged rooftop units using field measurements and building energy simulation

Packaged air-conditioning units are widely used in commercial buildings. Most packaged units in the field are equipped with constant-speed supply fans and constant-speed compressors. Many efforts have been made to increase the operational efficiency of packaged air conditioners by retrofitting existing units with improved controls or developing innovative products with advanced designs. This paper evaluates the energy performance of a packaged unit with all variable-speed components, including the supply fan, the compressor, and the condenser fan. Both a field test and energy simulation are used to quantify the potential of energy savings from the variable-speed unit (VSU) against reference units. In the field test, the reference is a six-year-old existing unit. It was determined through monitoring for one year that the VSU had a 31% higher cooling efficiency than the reference unit. In the simulation, a retail building model was used to compare the performance between the VSU and two reference units—one representing existing units in the field and the other representing units meeting the latest energy code requirements by ASHRAE Standard 90.1. Simulation results showed that depending on the climate, the VSU can save electricity consumption (including both cooling and fan) by 45%–54% relative to the first reference and by 22%–29% relative to the second reference. These findings are valuable for building designers and contractors in selecting packaged rooftop units for both new constructions and retrofits.

Experimental comparison of an air-to-water refrigeration system working with R134a and R1234yf

In this work, the use of R1234yf as a drop-in replacement for R134a in an air to water refrigeration system used to produce cool water at 7 °C is studied. This equipment was constructed in our laboratory with a minichannel heat exchanger working as condenser and a plate heat exchanger working as evaporator resulting in a 2.5 kW water chiller, which initially was working with R134a as refrigerant. A brief description of the refrigeration system and the installation used to test its behaviour as well as the uncertainty analysis is presented.Then, the test matrix defined in order to evaluate the effect of the different variables of interest on the performance of the refrigeration cycle is also presented. Air inlet temperature in the condenser was varied in order to analyse the influence of a variation in the ambient temperature. Other variables were varied in order to analyse the influence of different operating conditions as a variation in the compressor frequency or in the condenser fan velocity (by varying air inlet velocity). Finally, the subcooling degree was varied in order to compare a system with refrigerant receiver (no subcooling) and a system without refrigerant receiver and different refrigerant charge (different subcooling).According to the results obtained, R1234yf performs worse than R134a, presenting lower cooling capacity and higher compressor consumption in all tests, with a global efficiency around 25% lower. This can be explained by its lower isentropic and volumetric efficiency, which could be related to the type of lubricant used.

Aerodynamic damping of an oscillating fan blade: Mesh-based and meshless fluid structure interaction analysis

An investigation is performed to determine the dynamic flow phenomena that dampen a fan blade’s oscillation amplitude using numerical fluid structure interaction (FSI) simulations. Both a mesh-based and meshless numerical model are used to perform the FSI simulation and are compared according to their accuracy, robustness and computational cost. The meshless FSI simulation is performed by coupling the Finite Pointset Method (FPM) with a simplified 1D beam model. Experimental results from a separate investigation are used to validate the two numerical models.This paper shows that both numerical models are suitable for modelling the aerodynamic damping of an axial fan used in an air cooled condenser fan unit. The observed flow effects include the formation and shedding of leading edge vortices, downwash, tip vortices and the added mass effect. Leading edge vortices are a major damping contributor and are found to mainly depend on the blade’s effective angle of attack. The mesh-based and meshless FSI simulations are able to predict the experimentally determined tip displacement within an accuracy of 13% for 5 out of 6 simulations.

Evaluation of a magnetic gear for air‐cooled condenser applications

In high-power industrial applications such as air-cooled condenser fans, excessive mechanical gear failures highlight a need to investigate possible alternatives. In this study, the concentric magnetic gear (CMG) is evaluated as a potential replacement for traditional mechanical gear. For a more objective comparison between the CMG and mechanical gear, a CMG is optimally designed in accordance with the performance specifications of an existing mechanical gear. The design is further refined for performance improvements taking into account mechanical strength requirements. Based on the design a CMG prototype is manufactured and experimentally evaluated against its mechanical counterpart under the same operating conditions. The performance of both gears achieved efficiency in the mid 90% range. The mechanical gear slightly outperformed the CMG under rated operating conditions. The large unbalanced magnetic forces within the CMG are likely responsible for the larger than expected no-load losses. With the advantage of overload protection, reduced maintenance requirements, the CMG could be a valid replacement for the mechanical gear.

Assessments of variable-speed equipment for packaged rooftop units (RTUs) in the United States

Packaged air-conditioning systems, such as rooftop units (RTUs), are widely used in small commercial buildings in the United States. Although new regulations and standards require new air-conditioning equipment to have multi-speed supply fan operation, most of the installed units employ fixed-speed supply fans. The electrical energy usage associated with constant volumetric air delivery fan systems is on the order of half the total RTU electrical energy usage because supply fans operate continuously during the occupied periods in commercial buildings for ventilation. In addition, compressors within RTUs typically feature single- or two-stage capacity controls leading to frequent unit cycling and thus, deteriorated performance in energy efficiency. This paper presents relatively comprehensive assessment results for three RTU variable-speed retrofit options: 1) retrofits of fixed-speed supply fans with variable-speed fans for single-compressor-speed units, 2) replacement of existing fixed-speed RTUs with RTUs having two-speed compressors with variable-speed supply fans and 3) retrofits of RTUs with new RTUs that incorporate variable-speed compressors and fans (indoor and outdoor). The assessment study involves parametric simulations across different building types and locations in the U.S. to understand the performance variation with respect to location and building use. Performance improvements in terms of energy efficiency, operation cost and indoor comfort delivery for the various retrofit options are demonstrated compared to conventional single-stage RTUs with constant speed supply fans. The assessment results show that all three retrofit options offer significant fan energy savings, but much smaller savings potential for compressor and condenser fan electricity consumption. The variable-speed-unit retrofit provides the highest cost savings potentials, ranging from 40 to 250 $ per rated cooling ton per year depending on the building type and location. In addition to efficiency and economic benefits, the two-stage-unit and variable-speed-unit retrofits also lead to improved indoor humidity regulation performance due to reduced unit cycling.

Energetic and exergetic optimized Rankine cycle for waste heat recovery in a cement factory

The cement industry is one of the largest industries with regard to energy consumption. In the current study, the waste heat from the chimneys of Sabzevar cement factory was used to generate power with the use of the steam cycle in order to improve the energy efficiency. The results revealed that the increase in the boiler pressure decreased the total amount of the recovered energy due to the increase in the final temperature of the exhaust gases. But, the steam cycle efficiency was increased. Therefore, there would be an optimum pressure for the recovery boiler based on the energy and exergy analyses. Accordingly, the maximum exergy absorption from the waste heat of the chimneys of Sabzevar cement factory occurred at the pressure of 891.8 kPa. Considering the work consumption of air-cooled condenser fans, the maximum net power occurred at the recovery boiler pressure of 1398 kPa. The highest overall energy and exergy efficiencies also occurred at this pressure. Moreover, the effects of the important operating parameters, including the maximum cycle temperature, environmental temperature and condenser pressure on the optimum pressure were investigated. Results indicated that the boiler optimum pressure was independent from the operating parameters and remained constant, when these parameters changed.