Air Conditioning Applications Research Articles

Efficiently remove submicron particles by a novel foldable electrostatically assisted air coarse filter

Electrostatic assisted air (EAA) coarse filters combine the benefits of electrostatic precipitators and fibrous filters, achieving high filtration efficiency for submicron particulate matters (PM), low pressure drop, and large dust-holding capacity. For application in heating, ventilation, and air conditioning (HVAC) systems, PM removal technology is required to work at high air duct velocity, for example, 1 to 3 m/s. However, both theory and experience have revealed that the pressure drop will increase at large airflow rates. Here, we developed a novel foldable EAA coarse filter by shaping the polarizing electrodes into a zigzag structure and folding the coarse filter between the electrodes. High filtration efficiency for submicron PM (85.0–94.0% for 0.3–0.5 µm PM, 92.0–96.5% for 0.5–1 µm PM) and low pressure drop (5.9–26.4 Pa) at high air duct velocity (1–3 m/s) are achieved by optimizing folding angle (θ) to 45°. We found that θ determines the shape of the PET fold and the nature of electric field, leading to different filtration performances. In order to get the module with better applicability, the optimum θ was determined simultaneously by both filtering velocity and effective polarizing area. The results are expected to facilitate the wide application of EAA coarse filters in HVAC systems for a healthy and energy-saving indoor environment.

Impact of the adsorbent materials and adsorber bed design on performance of the adsorption thermophysical battery: Experimental study

The adsorption thermophysical battery (ATB) is considered one of the solutions for energy shortage problems in many energy-stressed countries. Various cheap energy resources such as, geothermal and solar energy can be used as power inputs in the ATB systems. This research offers an experimental study into the influence of utilizing two different types of adsorber bed units. The experimental setup has been designed to allow testing of two adsorber beds; conventional ABU and modified ABU (MABU) for improving ATB performance for air conditioning applications. Three adsorbents, namely, silica gel-RD, silica gel-blue and MCM-41with water refrigerant as working pairs were examined. The results revealed that, the refrigerant vapor uptake at temperature 30 °C increased by 36%, 43% and 16% for silica gel-RD, silica gel-blue and MCM-41 respectively compared with that at 35 °C. The outlet chilled coolant temperature in the case of MABU was decreased by 17%, 15% and 18.5% for silica gel-RD, silica gel-blue and MCM-41, respectively, compared with ABU. The results revealed an enhancement in COP using MABU and SCP in the case of using ABU, by 18%, 16% and 15% and by 12%, 17% and 27% for silica gel-RD, silica gel-blue and MCM-41 respectively.

Performance evaluation of a gaseous pollution control device suitable for in situ heating, ventilation and air conditioning applications

Performance evaluation of a gaseous pollution control device suitable for in situ heating, ventilation and air conditioning applications

High efficiency 3-D printed microchannel polymer heat exchangers for air conditioning applications

The design, fabrication, and experimental characterization of a counterflow Micro-pin array Polymer Heat eXchanger (MPHX) for HVAC applications is described. The design consists of water flow through microscale pin array plates, and airflow paths in a counterflow direction through adjacent rectangular channels. When compared to a Finned Tube Heat eXchanger (FTHX), the water plates take the place of fins and the crossflow tube bank is eliminated. The MPHX is fabricated by 3 D printing using a digital light synthesis method. A correlation-based model is developed and used to explore the parametric space to arrive at a baseline MPHX core geometry. Mechanical and fluidic simulations are performed on the baseline geometry to further develop the design. A sub-scale MPHX with a nominal cross duct area of 10.1 cm × 20.3 cm is designed and fabricated. Its thermal performance over a range of air and water flow rates corresponding to heat capacity rate ratios in the range of 0.25–1 is investigated. Results show that the effectiveness varies from 0.65 to 0.95 corresponding to a of 1 to 0.25. The experimental data are used to validate a correlation-based thermo-fluidic model of the MPHX. The validated model is further used to compare the performance advantages of the MPHX design over a FTHX. For a given heat exchanger volume and thermo-fluidic conditions, the MPHX transfers 55% more thermal energy when compared to a FTHX at comparable air-side pressure drops.

Economic analysis of refrigerant blend compared to conventional R-134a based on Power consumption for air conditioning application

Economic analysis of refrigerant blend compared to conventional R-134a based on Power consumption for air conditioning application

Experimental Study of the Unconstrained Melting of a Phase Change Material for Air-Conditioning Applications

Experimental Study of the Unconstrained Melting of a Phase Change Material for Air-Conditioning Applications

Cooling storage performance of a novel phase change material nano-emulsion for room air-conditioning in a self-designed pilot thermal storage unit

The dynamic stability of phase change material (PCM) emulsions is a crucial factor for their practical applications. So far most previous studies on PCM emulsions have been focused on the static stability in the laboratory and cooling performance in small scale systems, but few or none on the dynamic stability and cooling performance in pilot- or larger-scale systems. This study was to evaluate the dynamic stability or service life and cooling storage performance of a novel PCM nano-emulsion for room air-conditioning application in a self-designed, pilot-scale latent heat thermal energy storage unit. The pilot unit was constructed with a chiller, a storage tank, three sets of ceiling panels, circulation pumps and flow control valves in a pipeline. The PCM nano-emulsion remained stable through 45 repeated charging and discharging cycles over a period of 70 days in the pilot unit and could be well regenerated for even longer period of operation. The PCM nano-emulsion retained a stable cooling capacity, e.g. with a discharging rate of 199.6 W in the 1st-5th cycles and 196.9 W in the 35th-40th cycles at a given flow rate. The droplet size increased to a maximum of ∼180 nm but was still small compared with many of the previously published ranges. Therefore, it is expected that the novel PCM nano-emulsion can have a long service life. Moreover, its volumetric thermal storage capacity was about 1.45 times higher than water in the range of 5.5–20 °C, with the highest average charging rate of about 1.4 kW during the phase transition process, and a high efficiency of ∼85% in the cooling energy release with no limitation by fast discharging flow rate, which make it favourable for practical situations.

A case study in the field of sustainability energy: Transient heat transfer analysis of an ice thermal storage system with boiling heat transfer process for air-conditioning application

A numerical study on transient heat transfer of shell and tube type ice thermal storage system is carried out based on the concept of a single u-tube borehole thermal network. Two tubes are arranged in the thermal storage tank in which glycol solution flows in one of the tubes, while a refrigerant flows in the other tube. In this study a boiling heat transfer of the refrigerant is considered to model the heat exchange among the ice storage, the refrigerant and the glycol solution which can be used for air-conditioning application. Temperature variation of all the three substances of the ice thermal storage system (i.e. the ice/water, glycol solution and the refrigerant) with depth has been determined for specified times. Also temperature history of all the three substances has been determined at specific depth of the thermal storage system. Finally the effect of mass flow rate of the refrigerant on the solidification process has been investigated with the numerical method. The transient boiling heat transfer of the refrigerant in the saturated region, the transient single-phase heat transfer process of the glycol solution and the refrigerant at the superheated region, and the solidification process of the ice thermal storage system were all investigated in this study.

Measurements of saturation pressures for the novel refrigerant R1132(E)

R1132(E) (trans-1,2-difluoroethylene, C2H2F2) is a potential next generation refrigerant to be utilized in air conditioning applications. This hydrofluoroolefin (HFO) refrigerant possesses an extremely low-GWP value below 1 and it is an excellent candidate for replacing R32 in blends such as R410A, which are subjected to local and international greenhouse gas regulations for limiting global warming. Two isochoric apparatus were used to measure the saturation pressures of R1132(E) from 240 K to its critical temperature. At the critical temperature, the critical pressure of R1132(E) was also directly measured. Twenty-four saturation pressures including the critical point were used for optimizing a Wagner-type equation representing the saturation pressure curve. The absolute average deviation of the saturation pressures of R1132(E) predicted by the model using the fitted parameters and the experimental data is 0.02%. The optimized Wagner-type equation of saturation pressures is used for determining the acentric factor of R1132(E) as 0.2433, which is further utilized for the prediction of the saturation pressures using the Peng-Robinson cubic equation of state within an absolute average deviation of 0.31%.

A Comparative Performance Study of an Ejector-Expansion Refrigeration Cycle Using R134a and its Alternatives: Application of Automobile Air Conditioning

In this study, the performance of ejector-expansion refrigeration cycle (EERC) with R134a alternative refrigerants (R152a, R1234yf, R404A, R407C, R507A and R600a) for automobile air-conditioning application is investigated numerically. The ejector is modeled with a constant mixing-pressure assumption taking into consideration the friction effect in the ejector mixing section. The studied refrigerants are compared based on the optimum area ratio, discharge temperature, compressor input power, volumetric cooling capacity, exergy destruction, COP, exergy efficiency and COP improvement. The results show that R152a and R1234yf have the closest performance to R134a and can be considered the most suitable alternative refrigerants for R134a. The COP and exergy efficiency are improved by 2.26% and 2.27%, respectively, using R152a compared to the use of R134a, whereas they are reduced by 2.89% and 2.88% using R1234yf. The volumetric cooling capacity is reduced for both R152a and R1234yf by 6.14% and 6.8%, respectively. In addition, the effect of compressor rotational speed on the performances is reported.

Experimental study of the swing compressor with two discharge channels for household air-conditioner applications

In this paper, a novel swing compressor with two discharge channels (SCTC) is introduced, which can be an alternative compressor applied in household air-conditioner. SCTC has two discharge ports. The first one without discharge valve operates at all shaft speed and the other one with a high stiffness discharge valve operates at high shaft speed, which is helpful to improve the service life of compressor and discharge valve. Additionally, the discharge close volume is eliminated and the liquid strike can be prevented. In order to obtain the performance of SCTC, a prototype has been tested at three different shaft speeds and its volumetric efficiency, adiabatic efficiency, COP and noise characteristic have been analyzed. The performance of SCTC is always better than that of the swing compressor with no valve (SCNV). Besides, compared with the conventional swing compressor, the COP of SCTC increases by 2.26% at the shaft speed of 1800 r•min−1.

Investigation of enhancement in the thermal response of phase change materials through nano powders

A major problem faced by Phase Change Materials (PCM) based latent heat thermal energy storage systems is the slow thermal response. In this study, the feasibility of nano phase change materials composites is investigated experimentally by using various types of nanoparticles in PCM, to improve thermal response by increasing the thermal conductivity. Heat transfer enhancement of PCM composites (RT26 and coconut oil) is achieved by acquiring better thermophysical properties through seeding nanoparticles in PCM. RT26 and coconut oil are beneficial due to the absence of corrosion to metallic containers. A thermal response investigation is conducted with a flat slab type latent heat thermal energy storage unit. It was observed that the increase in thermal conductivity of PCM by seeding nanoparticles is useful for the improvement of heat transfer. Carbon nanotubes have shown better performance as compared to Al2O3 and Fe3O4 nanoparticles. It was further analyzed that at a 1 wt percent concentration of nanoparticles, the maximum heat transfer enhancement in RT26 caused by Fe3O4, Al2O3 and carbon nanotubes nanocomposites is up to 20.01, 36.68 and 64.21% respectively. The maximum heat transfer enhancement in coconut oil caused by Fe3O4, Al2O3 and carbon nanotubes nanocomposites is up to 8.83, 14.84 and 33.38% respectively. Therefore, it is revealed that RT26 has more potential for heat transfer enhancement as compared to coconut oil. This is due to the percentage improvement in the thermophysical response of RT26 as compared to coconut oil. The economic and environmental analysis was conducted to compare the performance of latent heat thermal energy storage unit with and without the application of nanoparticles in PCM, to estimate the most viable candidate among various nano composites. The economic analysis presented the lowest annual energy running cost and Net Present Value(NPV) for nanocomposite of carbon nanotubes in RT26 is Rs.-4381 and RS.-36375 respectively. Whereas the maximum annual energy cost and NPV for pure RT26 are Rs.-12240 and Rs. -75548 respectively. The NPV for Fe3O4 and Al2O3 is Rs.-62207 and Rs.-53062 respectively. The cost and NPV were Rs.-6646 and Rs.-55226 in the case of carbon nanotubes in coconut oil. It shows that the trend is the same in the case of Fe3O4 and Al2O3 nanoparticles in both RT26 and coconut oil, unlike of carbon nanotubes. The environmental analysis shows that the maximum and minimum payments of carbon dioxide by carbon nanotubes and Fe3O4 nano composites respectively in RT26, are Rs.7000 and Rs.2176. While the corresponding values are Rs.2975 and Rs.798 in the case of coconut oil. Hence, carbon nanotubes in RT26 have the highest economic and environmental viability. Accordingly, the enhancement in heat transfer using these nanoparticles will be helpful in air conditioning applications like animal houses.

Drop-in and retrofit refrigerants as replacement possibilities of R134a in domestic/commercial refrigeration and automobile air conditioner applications

According to the EU F-gas Regulation, the phase-out of the high global warming potential (GWP) refrigerants (with higher than 150 GWP value) had been established. The most currently existing household and commercial refrigerators and automobile air conditioners applications based on single-stage vapour compression systems operate with R134a as working fluid. The present paper aims, to review and evaluate the performance of a set of eco-friendly alternatives refrigerants to replace R134a, without change or with minor modifications in refrigeration equipment. The theoretical and experimental studies performed in this field of research were reviewed for this objective. These alternative refrigerants are some of HFCs, HFOs and HCs and their mixtures, which are expected to be an excellent candidates in many refrigeration applications. There are Many replacement possibilities had been proposed viz. drop-in replacement, retrofit refrigerant, and new systems. The results exhibited that the most suitable refrigerants as R134a drop-in substitutes are R1234yf, R152a, R450A, and R513A. The pure R1234ze and its mixtures are not suitable drop-in replacements of R134a but can be a good alternative to R134a only in new refrigeration systems. In terms of hydrocarbon refrigerants R290, R600, and R600a could replace R134a with some modifications to existing refrigeration systems to overcome the flammability issue. We should be using certain HFC and HC mixtures with the lowest TEWI index.

Heat Integration for the Air-Conditioning Application using Waste Heat Recovery in the Cast Iron Industry

The energy demand in the cast iron industry has been increasing for the past decades. Besides this, there is also high-energy demand for air conditioning, especially in the hot climate of the United Arab Emirates (UAE). Process integration tools can identify and measures the potential of energy saving via Heat Integration. The current paper presented a case study for industrial buildings' cooling demand via absorption chiller utilizing waste heat from a cast iron industry located in the Emirates Industrial Area, Sharjah, UAE. The Heat Integration approach has been applied via Pinch Analysis and Problem Table Algorithm to identify the minimum hot and cold utilities. Hot streams consist of four high-temperature furnaces exit gases. The heat exchanger network has been designed to fulfill the energy requirement using ProSim Simulis Pinch software (version 2.0). The minimum hot and cold utilities were predicted at 8,793 W and 1,600 W. The Pinch Point was found at 30 (C with more than 80 % of energy recovery. Moreover, the current study can achieve the lowest fuel consumption with fewer emissions, reduced utility consumption, less cost, and superior performance. The paper also includes several recommendations for the improvement of the cast iron industry's overall efficiency.

Dual-Mode Polymer-Based Temperature Sensor by Dedoping of Electrochemically Doped, Conjugated Polymer Thin Films

Polymer temperature sensors are important for applications in food packaging, air conditioning, wearable devices, and biomedicine. However, the sensing range of these sensors is narrow, and the mod...

USING ADSORPTION CHILLER IN SOLAR COOLING: ECONOMIC BENEFITS FOR JORDAN

Jordan has been facing a rigorous economic problem related to the high cost of energy. One of the main reasons is the cost of subsiding imported fuels to produce electricity for its domestic uses. The importation of energy represents more than 10% of its Gross Domestic Product (GDP) despite it has plentiful resources of renewable energy that can cover all its needs from electrical energy, while the national resources of energy in Jordan cover only 3-4% of the country's energy needs. This study investigates the potential of using the technology of Cooling Air by Solar Energy (CASE) for Air-conditioning applications to minimize the consumption of energy in Jordan. The main objectives of this work are to provide an overview of different commercially available CASE technologies and analyze the economic feasibility of selected CASE technology. The study of the economic feasibility has been done on the CASE technologies used for four scenarios. Analysis of data collection and assessment of economic viability in comparison to conventional VCC was also investigated. The results showed the relevance of the economic feasibility with the cost of electricity tariff, it also showed that the use of this device is feasible at a high electricity tariff; while there is a high risk on feasibility at a low electricity tariff.Keywords: adsorption chillers; vapor compression chillers; economic feasibilityJEL Classifications: C54, Q20, Q43, Q55DOI: https://doi.org/10.32479/ijeep.11752

Test and Analysis of Stepper Motor’s Noise in HVAC’s Ventilation Valve

With the application of automotive air conditioning being more popular, higher requirements on automotive air conditioning’s comfort have been put forward, noise is an important criterion about comfort. BDC motor controlling ventilation valve’s noise is mainly caused by brush and commutator, but stepper motor doesn’t have it and stepper motor is cheap and easy-controlling. In this paper, the principle of microstepping drive technology is discussed in detail, the control circuit block diagram and the application of the stepping motor’s control system are introduced. The noise of BDC motor and stepper motor controlling ventilation valve is measured in the semi-anechoic room, BDC motor produces peak noise at the start and stop during the working of motor, stepper motor’s noise is slight and smooth-going; current waveforms have been measured in the microstepping drive, the results show microstepping drive makes current waveform more smooth-going and stepper motor’s noise is lower. So it is a tendance stepper motor will replace BDC motor to control ventilation valve, and the microstepping drive can meet different requirements for merchant’s control.

Flow boiling of hydrocarbons and their zeotropic binary mixtures under pre- and post-dryout conditions

This paper concerns an experimental evaluation of the flow boiling heat transfer coefficient of R290, R600a and R1270 focusing on the replacement of R134a in commercial, and residential air-conditioning and refrigeration applications. Moreover, new zeotropic binary mixtures (R600a/R290, 70/30% molar fraction, and R600a/R1270, 75/25% molar fraction) with similar range of temperature applications than R134a are proposed and evaluated. Experiments are performed inside a conduit with a diameter of 9.43 mm for mass velocity ranging from 50 to 300 kg/(m2 s), local heat flux from 10 to 30 kW/m2, vapor quality from 0 to 1, and saturation temperature of 5 °C. In general, higher heat transfer coefficients are obtained for pure hydrocarbons, followed by the mixtures, therefore, showing a better heat transfer performance than R134a. Similar heat transfer coefficients are noticed among pure hydrocarbons, with R600a presenting slightly higher values under certain conditions. A behavior typical of heat transfer dominated by convective effects is noticed for the hydrocarbons with increasing quality at mass velocities higher than 100 kg/(m2 s), while for R134a such a behavior is verified only for mass velocities higher than 200 kg/(m2 s). Nucleate boiling dominated heat transfer is noticed only for mass velocities lower than 100 kg/(m2 s) and 200 kg/(m2 s) for hydrocarbons and R134a, respectively. In general, the heat transfer coefficient increases with mass velocity and heat flux. The heat transfer coefficient and dryout incipience vapor quality data are compared against prediction methods from literature, however, none predicting the current data. Generally, lower dryout incipience vapor qualities are noticed for the hydrocarbons compared to R134a, with the R600a presenting the lowest values. The dryout is delayed in terms of vapor quality for the mixtures compared to the pure hydrocarbons.

Review of Desiccant in the Drying and Air-Conditioning Application

Desiccant is a hygroscopic substance generally used in the dryer and air-conditioning system as a drying agent. The function of desiccant is to remove moisture from the air to reduce the humidity of the surrounding air been conditioned. This paper presents several works on the performance of desiccant material in the drying and air-conditioning application. It puts focus on the various advantages and disadvantages of the use of desiccant as a drying agent. There are some advantages of using desiccant include consistent drying and low energy usage. However, there are several disadvantages of using desiccants which are low capacity for moisture absorption and pressure drop in solid desiccant. Solar drying applications have some advantages such as being comparatively cheaper than other methods and less risk of spoiling the product. On the contrary, drying applications have disadvantages include being lower in comparison to the original foodstuff and drying foods eventually leads to shrinkage. The advantages of using desiccant in air-conditioning applications offer dehumidified fresh air to keep the building's temperature in a comfortable range and enhances water recovery efficiency. There are disadvantages such as desiccant will substantially impact the system's performance and desiccant should be cooled after completely dried.

Numerical investigation on a heat-driven free-piston thermoacoustic-Stirling refrigeration system with a unique configuration for recovering low-to-medium grade waste heat

• A novel heat-driven free-piston thermoacoustic Stirling cooling system is proposed. • The direct-coupling and single displacer configuration is introduced in the system. • The influences of various operating conditions are systematically analyzed. • It can achieve a COP above 0.60 below a heating temperature of 300°C. In this paper, a unique heat-driven free-piston thermoacoustic-Stirling refrigeration configuration is proposed to effectively provide room-temperature cooling by using low/medium-grade waste heat. Compared with the traditional duplex free-piston Stirling refrigerator, the unique feature of the proposed novel configuration is that it has only one single moving displacer and uses a thermal buffer tube to directly couple a thermoacoustic heat engine and a refrigerator, consequently leading to higher reliability and compactness. Numerical simulation and analysis have been conducted, focusing on the acoustical and thermodynamic characteristics as well as its global cooling performance. The thermoacoustic characteristics of the system are analyzed in details to understand its operating mechanism and cooling performance. Additional analyses are focused on the influences of the heating temperature and the working pressure on the thermodynamic performances of this system. A 2kW-class case study for air-conditioning refrigeration application shows that it can achieve a COP (coefficient of performance) of more than 0.62 at a refrigeration temperature of 10°C, under the conditions of an ambient temperature of 50°C and a heating temperature of 300°C. Its compactness and high efficiency are very competitive to the current heat-driven refrigerators, showing great potential in compact air-conditioning application by utilizing low-to-medium grade waste heat sources.