Residential Air Conditioning Research Articles

Modeling global residential sector energy demand for heating and air conditioning in the context of climate change

In this article, we assess the potential development of energy use for future residential heating and air conditioning in the context of climate change. In a reference scenario, global energy demand for heating is projected to increase until 2030 and then stabilize. In contrast, energy demand for air conditioning is projected to increase rapidly over the whole 2000–2100 period, mostly driven by income growth. The associated CO 2 emissions for both heating and cooling increase from 0.8 Gt C in 2000 to 2.2 Gt C in 2100, i.e. about 12% of total CO 2 emissions from energy use (the strongest increase occurs in Asia). The net effect of climate change on global energy use and emissions is relatively small as decreases in heating are compensated for by increases in cooling. However, impacts on heating and cooling individually are considerable in this scenario, with heating energy demand decreased by 34% worldwide by 2100 as a result of climate change, and air-conditioning energy demand increased by 72%. At the regional scale considerable impacts can be seen, particularly in South Asia, where energy demand for residential air conditioning could increase by around 50% due to climate change, compared with the situation without climate change.

Incorporating fan control into air-conditioning systems to improve energy efficiency and transient response

Modern air-conditioners frequently incorporate variable-speed compressors and variable-opening expansion valves with feedback control to improve performance and power efficiency. Because making the fan speeds adjustable adds flexibility to the control design and thus can lead to further improvements in performance and efficiency, this paper proposes two control algorithms, respectively, incorporating the outdoor fan and the indoor fan as the additional control inputs for air-conditioning systems. Both of the control algorithms are designed based on a low-order, linear model obtained from system identification. The first algorithm, which modulates the outdoor fan speed, can reduce the steady state power consumption if the temperature difference between the condenser and the outdoor environment is controlled properly. The second algorithm, which adds one more degree of freedom to control by modulating the indoor fan speed, can improve the transient response because actuator saturations become less likely to occur. The two control algorithms are implemented on a split-type residential air-conditioner and their respective performance is validated experimentally.

Speculation in the feasibility of evaporative cooling

The use of evaporative air cooling, for residential air conditioning, cannot be taken for granted in all situations. It depends on the climatic conditions and the specific nature of application. This work establishes a general foundation for judging the feasibility of evaporative cooling with different evaporative-system configurations, under different climatic conditions and for different applications. Two feasibility criteria were stipulated; the rate of air supply to space and the indoor relative humidity. Systematic procedures are presented for evaluating the required air-flow rate and predicting the achievable indoor condition. Explicit mathematical expressions are derived to define the limitations on outdoor conditions for any allowable specific air flow. The impacts of various pertinent factors are investigated. These include the required indoor temperature, the quality of space load represented by its SHF and the performance index of the system. Computer programs were devised to automate, hence facilitate, the repetitive computations and to evade the graphical work on the psychrometric chart. Samples of program results are graphically displayed.

Residential air conditioning and heating by means of enhanced solar collectors coupled to an adsorption system

This work explores the possibility to perform heating and air-conditioning of state of the art building located near Paris in France. For air-conditioning, enhanced compound parabolic solar collectors are used as a heat source of an adsorption system (methanol/activated carbon), while during winter direct coupling with the building is performed. A model describing the adsorption unit, the solar collectors and the house was used to simulate the performances of such an installation. For air-conditioning, thermal comfort is achieved as indoor temperature is kept below 25 °C during five consecutive hot days (heat wave effect), contrarily to the case for which only free-cooling during nighttime is used. For heating, the indoor temperature remains below the comfort temperature value by 2 K. Nevertheless, the auxiliary heating need will remain limited so that savings on electricity or fossil fuel consumption will be possible.

Explaining the spread of residential air conditioning, 1955–1980

In 1955 fewer than 2% of the nation’s residences had air conditioning; by 1980 over half were air conditioned, and over a quarter had central air. This paper attempts to explain the growth and the geographic differences in the prevalence of residential air conditioning from the mid fifties to 1980. Census data and data on climate and relevant prices are combined to estimate a model that focuses on the role of economic factors, that is, geographic differences and changes over time in incomes and prices, in affecting the pattern of diffusion of residential air conditioning.

Experimental performance of R432A to replace R22 in residential air-conditioners and heat pumps

In this study, thermodynamic performance of R432A and HCFC22 is measured in a heat pump bench tester under both air-conditioning and heat pumping conditions. R432A has no ozone depletion potential and very low greenhouse warming potential of less than 5. R432A also offers a similar vapor pressure to HCFC22 for ‘drop-in’ replacement. Test results showed that the coefficient of performance and capacity of R432A are 8.5–8.7% and 1.9–6.4% higher than those of HCFC22 for both conditions. The compressor discharge temperature of R432A is 14.1–17.3 °C lower than that of HCFC22 while the amount of charge for R432A is 50% lower than that of HCFC22 due to its low density. Overall, R432A is a good long term ‘drop-in’ environmentally friendly alternative to replace HCFC22 in residential air-conditioners and heat pumps due to its excellent thermodynamic and environmental properties.

Energy‐Saving Technologies for Inverter Air Conditioners

AbstractAlmost all residential air conditioners in Japan are inverter air conditioners in which a permanent magnet synchronous motor (PMSM) is driven by a PWM inverter. The inverter technology can reduce the energy consumption to less than half that of air conditioners driven by a constant‐speed induction motor (IM). This paper reviews the trends and the latest energy‐efficient technologies for the motor and the power converter that achieve considerable energy saving. Copyright © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Performance of R433A for replacing HCFC22 used in residential air-conditioners and heat pumps

In this study, thermodynamic performance of R433A and HCFC22 is measured in a heat pump bench tester under air-conditioning and heat pumping conditions. R433A has no ozone depletion potential and very low greenhouse warming potential of less than 5. R433A also offers a similar vapor pressure to HCFC22 for possible ‘drop-in’ replacement. Test results showed that the coefficient of performance of R433A is 4.9–7.6% higher than that of HCFC22 while the capacity of R433A is 1.0–5.5% lower than that of HCFC22 for both conditions. The compressor discharge temperature of R433A is 22.6–27.9°C lower than that of HCFC22 while the amount of charge for R433A is 57.0–57.7% lower than that of HCFC22 due to its low density. Overall, R433A is a good long term environmentally friendly alternative to replace HCFC22 in residential air-conditioners and heat pumps due to its excellent thermodynamic and environmental properties with minor adjustments.

Performance of a new refrigeration cycle using refrigerant mixture R32/R134a for residential air-conditioner applications

In this paper, a new refrigeration cycle (NRC) using the binary non-azeotropic refrigerant mixture R32/R134a is presented, which can be an alternative refrigeration cycle applied in residential air-conditioner. In the NRC, refrigerant circuit of the evaporator is separated into two branches. Because the non-azeotropic mixture has the characteristic of temperature glide, an important benefit of such configuration is that the Lorentz cycle can be realized. Compared with that of conventional cycle configuration, the new cycle efficiency can be improved. The calculating results show that, in the conventional refrigeration cycle (CRC), the mixture R32/R134a has a close performance to that is obtainable with pure refrigerant R22. However, the mixture R32/R134a in the NRC will result in a better performance. The maximal COP can be improved in a range of 8–9% over that of the CRC, and the volumetric refrigerating capacity can be approximately increased by 9.5%.

Design of a steady-state detector for fault detection and diagnosis of a residential air conditioner

This paper presents a general methodology for developing a steady-state detector for a vapor compression system based on a moving window and using standard deviations of seven measurements selected as features. The feature thresholds and optimized moving window size were based upon steady-state no-fault tests and startup transient tests. The study showed that evaporator superheat and condenser subcooling were sufficient for determining the onset of steady-state during the startup transient. However, they misidentified steady-state during indoor temperature change tests where evaporator saturation temperature and air temperature change across the evaporator were needed for proper steady-state identification. Hence, the paper recommends including all fault detection and diagnosis (FDD) features in the steady-state detector to ensure the robustness of the detector because different features may play key roles with different transients.

Performance comparison of microchannel evaporators with refrigerant R-22

An experimental study on the performance comparison of microchannel evaporators with refrigerant R-22 was conducted. Six microchannel evaporators were designed and manufactured for a residential air-conditioner. They were tested with psychrometric calorimeter test facilities. The experiment was performed with both vapor compression system and refrigerant circulation system. Each evaporator was made up of two parallel flow heat exchangers connected with several return pipes. The parallel flow heat exchanger had 41 microchannel tubes inserted between inlet and outlet headers. The microchannel tube had 8 rectangular ports with the hydraulic diameter of 1.3 mm. For the vapor compression system, the flow area ratio and the number of return pipes had a great effect on the cooling capacity. Type 3 with a flow area ratio of 73% and 58% showed the best cooling capacity. It had 12 return pipes and 3 circuits. There is a merging manifold in it. The effect of the number of circuits and merging manifold on the cooling capacity was relatively small. For the refrigerant circulation system, the effect of the mass flow rate on the cooling capacity was slightly superior to that of inlet quality. The effect of the number of circuits on the cooling capacity was different from the result of the vapor compression system. The effect of merging manifold was negligible, which was consistent with the result of the vapor compression system. The cooling capacity proportionally increased as the vertical inclination angle of the evaporator increased due to gravity force.

Flow Characteristics of Refrigerants Flowing Inside an Adiabatic Spiral Capillary Tube

An analytical model has been developed to predict the length of adiabatic capillary tubes used in domestic refrigerators and low-capacity residential air conditioners. The model predicts the length of two types of tubes—straight and spiral adiabatic capillary tubes. The proposed model is based on the homogenous two-phase flow model, which predicts the length of the adiabatic capillary tubes as a function of refrigerant mass flow rate, capillary tube diameter, degree of subcooling at capillary inlet, internal surface roughness, and the pitch of the Archimedean spiral. The existence of subcooled liquid at the entry of the capillary tube requires the computation of single-phase and then two-phase lengths of the tube. The McAdams et al. (1942) viscosity correlation has been used to evaluate the two-phase viscosity of the expanding refrigerant in the latter part of the capillary tube. All the thermophysical and transport properties of the refrigerants are evaluated by the REFPROP Version 7 database, which is based on the Carnahan-Starling-DeSantis equation of state. The simulation results are validated with the experimental findings of previous researchers. The performance of the above two geometries of adiabatic capillary tube is compared, and it is established that for the same state of refrigerants at the inlet and exit of the adiabatic capillary, spiral capillary is found to have a shorter length. Parametric study of the adiabatic capillary tubes is also carried out. Further, the effect of geometric and physical parameters has been presented in detail. A much smaller capillary tube is required when the eco-friendly refrigerants R-134a and R-152a are used in place of refrigerant R-12 for similar conditions across the adiabatic spiral capillary tube.

A comparative study on the performance and environmental characteristics of R410A and R22 residential air conditioners

R410A is a long-term alternative refrigerant with zero ODP (ozone-depleting-potential) for replacing R22. In this paper, four sets of comparable R410A and R22 split-type residential A/C (air conditioners) were developed and then their performance was comparatively studied using one simulation software. The A/C performance compared in this paper included the cooling capacity, EER (energy efficiency ratio), annual power consumption of A/C and the global warming impact of refrigerants adopted by the A/C. It was concluded that the adoption of R410A could be helpful for A/C to decrease their heat exchanger size or improve their operation efficiency for power saving. Moreover, compared to R22, R410A could in fact help alleviate its overall impact on global warming through significantly reducing the indirect global warming impact caused by operating R410A A/C.

Performance of alternative refrigerants for residential air-conditioning applications

In this study, performances of two pure hydrocarbons and seven mixtures composed of propylene, propane, HFC152a, and dimethylether were measured to substitute for HCFC22 in residential air-conditioners and heat pumps. Thermodynamic cycle analysis was carried out to determine the optimum compositions before testing and actual tests were performed in a breadboard-type laboratory heat pump/air-conditioner at the evaporation and condensation temperatures of 7 and 45 °C, respectively. Test results show that the coefficient of performance of these mixtures is up to 5.7% higher than that of HCFC22. While propane showed a 11.5% reduction in capacity, most of the fluids had a similar capacity to that of HCFC22. For these fluids, compressor-discharge temperatures were reduced by 11–17 °C. For all fluids tested, the amount of charge was reduced by up to 55% as compared to HCFC22. Overall, these fluids provide good performances with reasonable energy-savings without any environmental problem and thus can be used as long-term alternatives for residential air-conditioning and heat-pumping applications.

Aspectos de contaminação biológica em filtros de condicionadores de ar instalados em domicílios da cidade de Manaus - AM

Este trabalho apresenta resultados da pesquisa de contaminação dos filtros de condicionadores de ar instalados no setor residencial da cidade de Manaus. A pesquisa foi realizada no âmbito do projeto CAEMA (Condicionadores de Ar, Energia e Meio Ambiente) que consistiu na troca de aparelhos de ar condicionado ineficientes por eficientes na zona urbana da cidade. Dos 500 condicionadores de ar retirados do sistema pelo projeto, foram selecionados 50 filtros (10%) para a análise de contaminação biológica, tendo sido identificada uma enorme variedade de agentes prejudiciais à saúde humana, entre bactérias e fungos. A bactéria mais vezes identificada foi a Staphylococcus sp e o fungo mais freqüente foi o Penicillium sp. Também foi possível verificar, por meio de entrevistas telefônicas junto a 37 usuários desses equipamentos, a grande incidência de sintomas associados a problemas de insuficiente qualidade de ar nos ambientes residenciais. Circunstâncias que motivaram a oportunidade desta pesquisa também impossibilitaram a coleta das amostras por unidade de volume, com os condicionadores ainda em funcionamento. Esse fato não comprometeu os objetivos da pesquisa, de promover a reflexão sobre os cuidados com a correta limpeza dos condicionadores de ar residenciais.

A Generalized Neural Network Model of Refrigerant Mass Flow Through Adiabatic Capillary Tubes and Short Tube Orifices

Adiabatic capillary tubes and short tube orifices are widely used as expansive devices in refrigeration, residential air conditioners, and heat pumps. In this paper, a generalized neural network has been developed to predict the mass flow rate through adiabatic capillary tubes and short tube orifices. The input/output parameters of the neural network are dimensionless and derived from the homogeneous equilibrium flow model. Three-layer backpropagation (BP) neural network is selected as a universal function approximator. Log sigmoid and pure linear transfer functions are used in the hidden layer and the output layer, respectively. The experimental data of R12, R22, R134a, R404A, R407C, R410A, and R600a from the open literature covering capillary and short tube geometries, subcooled and two-phase inlet conditions, are collected for the BP network training and testing. Compared with experimental data, the overall average and standard deviations of the proposed neural network are 0.75% and 8.27% of the measured mass flow rates, respectively.

Analysis and Evaluation of Residential Air Conditioners for Power System Studies

Air conditioners deserve special attention because they represent a significant part of the power system load, mainly in high temperature regions. This work takes into account conventional and variable-speed types, as the latter one presents two possible arrangements, i.e., with and without undervoltage protection. The modeling of equipments is analyzed for simulation purposes, as a novel representation of variable-speed units with undervoltage protection is introduced. The behavior of each air conditioner is verified in steady state operation considering typical power quality and voltage disturbances that occur in power systems such as voltage sags and interruptions. Furthermore, the influence of the aforementioned equipment on the power system is analyzed within the context of a distribution network

人工気候室における測定結果に基づく冷暖房COPの部分負荷特性 : ルームエアコンディショナの冷暖房COPおよびエネルギー消費量に関する研究その1

人工気候室における測定結果に基づく冷暖房COPの部分負荷特性 : ルームエアコンディショナの冷暖房COPおよびエネルギー消費量に関する研究その1

Thermodynamic performance of HCFC22 alternative refrigerants for residential air-conditioning applications

In this study, thermodynamic performance of two pure hydrocarbons and seven mixtures composed of propylene (R1270), propane (R290), HFC152a, and dimethylether (RE170, DME) was measured in an attempt to substitute HCFC22 in residential air-conditioners. The pure and mixed refrigerants tested have greenhouse warming potentials (GWPs) of 3–58 as compared to that of CO 2 and the mixtures are all near-azeotropic having the gliding temperature difference (GTD) of less than 0.6 °C. Thermodynamic cycle analysis was carried out to determine the optimum compositions before testing and actual tests were performed in a breadboard type laboratory heat pump/air-conditioner at the evaporation and condensation temperatures of 7 and 45 °C, respectively. Test results show that the coefficient of performance (COP) of these mixtures is up to 5.7% higher than that of HCFC22. While propane showed 11.5% reduction in capacity, most of the fluids had the similar capacity to that of HCFC22. Compressor discharge temperatures were reduced by 11–17 °C with these fluids. There was no problem found with mineral oil since the mixtures were mainly composed of hydrocarbons. The amount of charge was reduced up to 55% as compared to HCFC22. Overall, these fluids provide good thermodynamic performance with reasonable energy savings without any environmental problem and thus can be used as long term alternatives for residential air-conditioning and heat pumping applications.

Identification and weather sensitivity of physically based model of residential air-conditioners for direct load control: A case study

In most electricity systems, the residential sector is one of the main contributors to system peaks. Hot and humid summer seasons lead to a significant proportion of the supplied power being used on air-conditioning (AC). In this work, we address the identification problem of the parameters of an aggregated elemental physically based model representing a housing unit with an AC system. The identification is done to validate the model using a pilothouse equipped with an independent air-conditioner system. An online maximum likelihood based-identification algorithm is developed. The required hardware and system instrumentation are detailed. A sensitivity analysis study of the model for variations in humidity and solar radiation is also reported. The results indicate that the physically based model succeeded to capture the effects of the outdoor conditions.