Effect of Air to Air Fixed Plate Enthalpy Energy Recovery Heat Exchanger Flow Profile on Air Conditioning System Energy Recovery

2016 ◽  
Vol 819 ◽  
pp. 245-249
Author(s):  
Mohammad Shakir Nasif ◽  
Rafat Al-Waked
Keyword(s):  
Heat Exchanger ◽  
Air Conditioning ◽  
Energy Recovery ◽  
Moisture Transfer ◽  
Flow Profile ◽  
Air Conditioner ◽  
Counter Flow ◽  
Flow Configuration ◽  
Fixed Plate ◽  
Cooling Coil

Fixed plate enthalpy heat exchanger which utilizes permeable material as heat and moisture transfer surface has been used as an energy recovery system to recover sensible and latent heat in HVAC systems. The heat exchanger effectiveness is affected by the air flow profile. It is well known that counter flow configuration provides highest effectiveness, however, in real applications, it is not possible to implement a counter flow configuration, as both inlet and outlet ducts of the two flow streams are located on the same side of the heat exchanger. Therefore, several quasi-counter-flow heat exchanger designs including Z-shaped, L-shaped, Z-shaped opposite flow configurations are proposed in this research and their effect on energy consumed by an air conditioning cooling coil has been investigated, where each of the proposed heat exchanger is incorporated in an air conditioning cooling coil model. The modeled cooling coil energy consumption and energy recovered by the heat exchangers are evaluated under Kuala Lumpur weather conditions. It has been found that an air conditioner coupled with L-shaped heat exchanger recorded up to 20% increase in energy recovery in comparison with Z-shaped oposite and Z-shaped heat exchanger.

scholarly journals Membrane Based Enthalpy Heat Exchanger Performance in HVAC System

2017 ◽  
Vol 2 (1) ◽  
Author(s):  
M. S. Nasif ◽  
G. L. Morrison ◽  
M. Behnia
Keyword(s):  
Mathematical Model ◽  
Heat Exchanger ◽  
Energy Recovery ◽  
System Analysis ◽  
Moisture Transfer ◽  
Cooling Capacity ◽  
Coefficient Of Performance ◽  
Air Conditioner ◽  
Hvac System ◽  
Heat And Moisture

The performance of a membrane based heat exchanger utilizing porous paper as the heat and moisture transfer media used in ventilation energy recovery systems is presented. A mathematical model was developed and validated against the experimental results. This model can be used for design aide to predict the effectiveness of the heat exchanger. Furthermore, system analysis of an air conditioner shows an increase in the coefficient of performance and cooling capacity when paper heat exchanger is used, especially in a climate similar to the weather in Malaysia and Darwin.

Experimental Research on Microchannel Heat Exchanger Performance for Residential Air Conditioner Applications

2009 ◽  
Author(s):  
Jianghong Wu ◽  
Shuangfeng Wang ◽  
Yunting Ge
Keyword(s):  
Heat Exchanger ◽  
Thermal Performance ◽  
Air Conditioning ◽  
The Other ◽  
Air Conditioner ◽  
Round Tube ◽  
Tube Heat Exchanger ◽  
Face Area ◽  
Residential Air Conditioning ◽  
Air Conditioning Systems

Two type condensers of R22 residential air conditioning systems were investigated in this study. Two R22 residential air-conditioning systems, one with a microchannel condenser and the other with a round-tube condenser, were examined experimentally, while the other components of the two systems were identical except the condensers. Based on the principle of the microchannel condensation, the analysis of heat transfer along parallel heat exchanger was conducted. The non-uniform air velocity distribution at the face of the microchannel condenser and refrigerant distribution in headers were taken into account in this research. The mechanism and possibility of the superior thermal performance as compared with conventional fin-tube heat exchangers were discussed. In addition, the maximum of thermal performance influenced by the running parameter was experimentally measured. The experimental results show that with one third face area of round tube heat exchanger, microchannel condenser’s pressure drop increase around 12–23% and refrigeration output increase 2–5%, refrigerant charge decreases around 50%, it is found to be a promising candidate for residential air conditioning condenser.

Mathematical Modeling for the Regenerator of Liquid Desiccant Air-Conditioning System

2013 ◽  
Vol 465-466 ◽  
pp. 226-231
Author(s):  
Majid Ali Wassan ◽  
Khairul Habib ◽  
Suhaimi B. Hassan
Keyword(s):  
Mathematical Model ◽  
Air Conditioning ◽  
Flow Direction ◽  
Model Performance ◽  
Dilute Solution ◽  
Liquid Desiccant ◽  
Humidity Ratio ◽  
Counter Flow ◽  
Air Conditioning System ◽  
Flow Configuration

T his paper presents mathematical model for regenerator of liquid desiccant air conditioning system. Regression analysis was used to get the relation between enthalpy and humidity ratio. Performance of regenerator is highly affected by varying the flow direction between air & desiccant thus to get proper regeneration results counter-flow configuration is considered. Previous studies show better regeneration results for counter-flow direction of air to desiccant. Validation is done by comparing results of present study the experimental results of previous studies and comparison was found to be quite satisfactory. Based on above mathematical model performance of regenerator was analyzed. The purpose of this research was regeneration of liquid desiccant from its dilute-solution form to strong-solution.

scholarly journals Multi-stage heat-pipe heat exchanger for improving energy efficiency of the HVAC system in a hospital operating room 1

2020 ◽  
Author(s):  
Ragil Sukarno ◽  
Nandy Putra ◽  
Imansyah Ibnu Hakim ◽  
Fadhil Fuad Rachman ◽  
Teuku Meurah Indra Mahlia
Keyword(s):  
Heat Exchanger ◽  
Air Conditioning ◽  
Energy Recovery ◽  
Heat Recovery ◽  
Heat Pipes ◽  
Inlet Temperature ◽  
Hvac System ◽  
Inlet Velocity ◽  
Air Inlet ◽  
Pipe Heat

Abstract The demands of specific requirements related to thermal comforts, such as temperature, relative humidity, inside air exchange and other factors required in a hospital operating rooms, have necessitated the development of energy-efficient heating, ventilation and air conditioning (HVAC) systems and efficient heat-recovery system using a heat-pipe heat exchanger (HPHE). The experiment was conducted by using HPHEs having three, six and nine rows, with four heat pipes in each row, arranged in a staggered configuration with a variation of fresh-air inlet temperature and velocity. The theoretical analysis was conducted using the ε-NTU method for predicting the effectiveness, outlet temperature of the evaporator side and energy recovery of the HPHE. The experimental results indicated that increasing the air-inlet temperature in the evaporator section and the number of rows increased the HPHE effectiveness but increasing the air-inlet velocity reduced the effectiveness. The highest effectiveness of 62.6% was obtained at an air-inlet temperature of 45°C with an air-inlet velocity of 2 m/s and a 9-row HPHE. The energy recovery of the HPHE increased with the number of rows, air-inlet temperature and air velocity in the evaporator section. The ε-NTU method can be used as a comparison method in the analysis of heat-recovery systems that apply HPHE air conditioning systems. Heat pipes that utilize cold-air exhaust from a room in an HVAC system can enhance efficiency and reduce emissions.

A Constant-Wall-Temperature Model for Prediction of Thermal Performance of Gas-to-Gas Counter-Flow and Parallel-Flow Microchannel Heat Exchangers

2011 ◽  
Author(s):  
Kohei Koyama
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Difference Method ◽  
Heat Exchangers ◽  
Parallel Flow ◽  
Counter Flow ◽  
Partition Wall ◽  
Transfer Rates ◽  
Flow Configuration ◽  
Microchannel Heat Exchanger

Thermal performances of gas-to-gas counter-flow and parallel-flow microchannel heat exchanger have been investigated. Working fluid used is air. Heat transfer rates of both heat exchangers are compared with those calculated by a conventional log-mean temperature difference method. The results show that the log-mean temperature difference method can be employed to a parallel-flow configuration whereas that cannot be employed to a counter-flow configuration. This study focuses on the partition wall which separates hot and cold passages of the microchannel heat exchanger. The partition wall is negligibly thin for a conventional-sized heat exchanger. In contrast, the partition wall is thick compared with channel dimensions for a microchannel heat exchanger. A model which includes the effect of the thick partition wall is proposed to predict thermal performances of the microchannel heat exchangers. The heat transfer rates obtained by the model agree well with those obtained by the experiments. Thermal performances of the counter-flow and parallel-flow microchannel heat exchangers are compared with respect to one another based on temperature of the partition wall. The comparison results show that thermal performances of the counter-flow and parallel-flow microchannel heat exchangers are identical. This is due to performance degradation induced by the thick partition wall of the counter-flow microchannel heat exchanger. This study reveals that the thick partition wall dominates thermal performance of a gas-to-gas microchannel heat exchanger.

The empirical study of a four-row heat pipe heat exchanger to predict the year-round energy recovery in the tropics

2011 ◽  
Vol 32 (4) ◽  
pp. 307-327 ◽  
Author(s):  
YH Yau ◽  
M Ahmadzadehtalatapeh
Keyword(s):  
Heat Exchanger ◽  
Heat Pipe ◽  
Heat Exchangers ◽  
Air Conditioning ◽  
Energy Recovery ◽  
Empirical Performance ◽  
Air Conditioning Systems ◽  
The Tropics ◽  
The Impact ◽  
Pipe Heat

The effect of heat pipe heat exchanger on the heat recovery was studied in the tropics. The performance of the heat exchanger was monitored during the one week of operation (168 h) to find out the performance characteristic curves. Three coil face velocities namely, 2, 2.2 and 2.5 m/s were tested and the temperature of return air was controlled at 24°C. The relevant empirical equations were then employed for the hour-by-hour prediction of the energy recovery by the heat pipe heat exchanger for the whole year. The impact of inside design temperature on the heat recovery by the heat exchanger was also studied. The thermal performance of the heat pipe heat exchanger was simulated based on the effectiveness-NTU method and the theoretical values were compared with the experimental data. Practical application: Performance improvement of the heating, ventilating and air conditioning systems is a challenge to the designers. The results obtained from this research work could serve as a practical guide for engineers who are intending to use heat pipe heat exchangers in the heating, ventilation and air conditioning systems operating in tropical climates. Engineers and researchers have the potential to use the recommended empirical performance equations to examine the impact of heat pipe heat exchangers on the performance of the current air conditioning systems. Moreover, these empirical performance equations enable the year-round operating effect of heat pipe heat exchangers on energy savings to be predicted realistically.

scholarly journals Design and Construction of a Double Pipe Heat Exchanger for Laboratory Application

2020 ◽  
Vol 5 (11) ◽  
pp. 1301-1306
Author(s):  
C. E. Ebieto ◽  
R. R. Ana ◽  
O. E. Nyong ◽  
E. G. Saturday
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Engineering Students ◽  
Counter Flow ◽  
Flow Configuration ◽  
Overall Heat Transfer Coefficient ◽  
Double Pipe ◽  
Pipe Heat

Engineering education is incomplete without laboratory practices. One of such laboratory equipment necessary for all engineering students to have hands-on in the course of their undergraduate studies is the heat exchanger. This work presents the detailed design and construction of a laboratory type double pipe heat exchanger that can be used both in the parallel and counter flow configuration. The heat exchanger was constructed using galvanized steel for both the tube and shell. Experiments were designed and carried out to test the performance of the heat exchangers. The heat exchanger performance characteristics (logarithm mean temperature difference (LMTD), heat transfer rate, effectiveness, and overall heat transfer coefficient) were obtained and compared for the two configurations. The LMTD tends to be relatively constant as the flow rate was increased for both the parallel and counter-flow configuration but with a higher value for the parallel flow configuration. The heat exchanger has a higher heat transfer rate, effectiveness, and overall heat transfer coefficient and therefore has more performance capability for the counter-flow configuration. The overall heat transfer coefficient increased as the flow rate increased for both configurations. Importantly, as a result of this project, Mechanical Engineering students can now have hands-on laboratory experience on how the double pipe heat exchanger works.

scholarly journals Experimental and Numerical Design and Optimization of a Counter-Flow Heat Exchanger

2018 ◽  
Vol 151 ◽  
pp. 02003
Author(s):  
Salman Bahrami ◽  
Mohammad Hassan Rahimian
Keyword(s):  
Heat Exchanger ◽  
Air Conditioning ◽  
Cooling System ◽  
Flow Behavior ◽  
Low Pressure ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Counter Flow ◽  
Air Conditioning System ◽  
Flow Heat

A new inexpensive counter-flow heat exchanger has been designed and optimized for a vapor-compression cooling system in this research. The main aim is to experimentally and numerically evaluate the effect of an internal heat exchanger (IHX) adaptation in an automotive air conditioning system. In this new design of IHX, the high-pressure liquid passes through the central channel and the low-pressure vapor flows in several parallel channels in the opposite direction. The experimental set-up has been made up of original components of the air conditioning system of a medium sedan car, specially designed and built to analyze vehicle A/C equipment under real operating conditions. The results show that this compact IHX may achieve up to 10% of the evaporator capacity while low pressure drop will be imposed on this refrigeration cycle. Also, they confirm considerable decrease of compressor power consumption (CPC), which is intensified at higher evaporator air flow. A significant improvement of the coefficient of performance (COP) is achieved with the IHX employment too. The influence of operating conditions has been also discussed in this paper. Finally, numerical analyses have been briefly presented, which bring more details of the flow behavior and heat transfer phenomena, and help to determine the optimal arrangement of channels.

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