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.

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 Numerical investigation on the effect of varying the number of flow dividers on Z-shaped membrane heat exchanger performance

2020 ◽  
Vol 16 (1) ◽  
pp. 85-89
Author(s):  
Mohammad Shakir Nasif ◽  
Ra'fat Al-Waked ◽  
Firas Ismail
Keyword(s):  
Heat Exchanger ◽  
Indoor Air ◽  
Energy Recovery ◽  
Heat Recovery ◽  
Cfd Simulation ◽  
Moisture Transfer ◽  
Flow Distribution ◽  
Building Energy ◽  
Minor Effect ◽  
Heat And Moisture

To reduce building energy consumption and to improve indoor air quality, it is necessary the use heat recovery such as air-to-air fixed-plates enthalpy heat exchanger in mechanical ventilation. Prediction of enthalpy performance by utilizing CFD simulation is challenging since most commercial software do not simulate moisture transfer. In this research, a Z-shaped membrane heat exchanger which is used for building energy recovery systems was modeled by using commercial CFD software (FLUENT). Kraft paper of 45 gsm was used as the heat exchanger heat and moisture transfer surface. A User Define Function (UDF) code was developed and incorporated in the CFD software to enable the software to model moisture transfer through the membrane. This model is used to investigate the performance of Z-Shaped heat exchanger when the number of flow dividers within the heat exchanger is varied. It was found that a 21 % increase in the effectiveness was achieved when the number of ribs was increased from no ribs to 5 ribs. However, increasing the number of ribs from 5 to 11 only demonstrates minor effect. Therefore, no significant improvement is noticed when the number of ribs is increased beyond 5 which is attributed to air flow distribution which because more uniform when number of ribs is increased. However, the flow is already uniform when 5 ribs where used, hence increasing the ribs to 11 will not improve the flow distribution further.

Mathematical Models of Papermaking

2001 ◽  
Vol 6 (1) ◽  
pp. 9-19 ◽  
Author(s):  
A. Buikis ◽  
J. Cepitis ◽  
H. Kalis ◽  
A. Reinfelds ◽  
A. Ancitis ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Initial Value Problems ◽  
Moisture Transfer ◽  
Bound Water ◽  
Drying Process ◽  
Initial Value ◽  
First Order ◽  
Heat And Moisture ◽  
The Mathematical Model ◽  
The Web

The mathematical model of wood drying based on detailed transport phenomena considering both heat and moisture transfer have been offered in article. The adjustment of this model to the drying process of papermaking is carried out for the range of moisture content corresponding to the period of drying in which vapour movement and bound water diffusion in the web are possible. By averaging as the desired models are obtained sequence of the initial value problems for systems of two nonlinear first order ordinary differential equations. 

scholarly journals The Effect of Refrigerant Charge and Outdoor Temperature on the Condenser and Evaporator of a Split-Unit Type Air Conditioner Using R22 Refrigerant

2018 ◽  
Vol 225 ◽  
pp. 02013
Author(s):  
Mohd Hazwan Yusof ◽  
Sulaiman Mohd Muslim ◽  
Muhammad Fadhli Suhaimi ◽  
Mohamad Firdaus Basrawi
Keyword(s):  
Cooling Capacity ◽  
Coefficient Of Performance ◽  
Air Conditioner ◽  
Outdoor Temperature ◽  
Unit Type ◽  
Small Capacity

To maintain the temperature setup on an air conditioner, the compressor will use more or less energy based on the outdoor temperature. Therefore, there is a need to understand the performance of the air conditioner if the outdoor temperature is varied. In this research, a used small capacity split-unit air conditioner using R-22 refrigerant is used to study the effect of outdoor temperature on the performance of the air conditioner. From the results, it can be understood that lower outdoor temperature requires less work from the compressor. The cooling capacity and coefficient of performance drop as the outdoor temperature increases.

scholarly journals Performance Evaluation of a Gravity-Assisted Heat Pipe-Based Indirect Evaporative Cooler

Energies ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 200 ◽  
Author(s):  
Krzysztof Rajski ◽  
Jan Danielewicz ◽  
Ewa Brychcy
Keyword(s):  
Mathematical Model ◽  
Heat Pipe ◽  
Cooling Capacity ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Mass Transfer Processes ◽  
Air Cooler ◽  
Evaporative Cooler ◽  
The Mathematical Model ◽  
Further Development

In the present work, the effects of different operating parameters on the performance of a gravity-assisted heat pipe-based indirect evaporative cooler (GAHP-based IEC) were investigated. The aim of the theoretical study is to evaluate accurately the cooling performance indicators, such as the coefficient of performance (COP), wet bulb effectiveness, and cooling capacity. To predict the effectiveness of the air cooler under a variety of conditions, the comprehensive calculation method was adopted. A mathematical model was developed to simulate numerically the heat and mass transfer processes. The mathematical model was validated adequately using experimental data from the literature. Based on the conducted numerical simulations, the most favorable ranges of operating conditions for the GAHP-based IEC were established. Moreover, the conducted studies could contribute to the further development of novel evaporative cooling systems employing gravity-assisted heat pipes as efficient equipment for transferring heat.

scholarly journals Investigation on the improvement of car air conditioning system performance using an ejector

2018 ◽  
Vol 197 ◽  
pp. 08013
Author(s):  
Enang Suma Arifianto ◽  
Ega Taqwali Berman ◽  
Mutaufiq Mutaufiq
Keyword(s):  
System Performance ◽  
Test Procedure ◽  
Cooling Capacity ◽  
Coefficient Of Performance ◽  
Working Fluid ◽  
Refrigeration Cycle ◽  
Air Conditioner ◽  
Air Conditioning System ◽  
Compressor Work ◽  
R 134A

The purpose of this research is to know the improvement of car air conditioner system performance using an ejector. The study was conducted on a car engine with power 100 PS (74 kW) @ 5000 rpm. The test procedure is carried out under two conditions: the normal refrigeration cycle mode and the refrigeration cycle mode with the ejector. The working fluid used in the refrigeration cycle is R-134a. Performance data was measured on engine revolutions ranging from 1500 - 3000 rpm. Finally, the results showed that ejector usage on AC system generates an increase in the refrigeration effect and coefficient of performance (COP) of 25% and 22%, respectively. This has implications to better cooling capacity and compressor work that is lighter.

scholarly journals Impacts of Room Temperature on the Performance of a Portable Propane Air Conditioner

2015 ◽  
Vol 23 (02) ◽  
pp. 1550015 ◽  
Author(s):  
Ahmad Sharifian ◽  
Jeri Tangalajuk Siang
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Room Temperature ◽  
Capillary Tube ◽  
Cooling Capacity ◽  
Coefficient Of Performance ◽  
Air Conditioner ◽  
Charge Condition ◽  
Full Charge

The performance of a portable propane air conditioner system, in which the temperatures of the air passing over the condenser and evaporator are equal, has been experimentally investigated under different room temperatures and refrigerant charge levels. The research has been carried out in a range of room temperatures from 20°C to 35°C and in undercharge, standard charge and overcharge conditions. The results show that, at higher room temperatures, the refrigerant temperature in all parts of the system, the density of the refrigerant at the inlet and outlet of the condenser, mass of the refrigerant in the compressor, the mass flow rate of the refrigerant and the cooling capacity of the system in either the undercharge or full charge condition, the specific cooling capacity of the undercharge system, the useful work of the compressor, and the maximum pressure of the refrigerant increase. The increase in room temperature decreases the density of the refrigerant at the inlet and outlet of the capillary tube, the mass of the refrigerant in the capillary tube, the refrigerant subcooling at the inlet of the capillary tube, the maximum velocity of the refrigerant and the coefficient of performance. In addition, the increase in room temperature at overcharge condition causes an increase in the mass flow rate, cooling capacity and specific cooling capacity to a maximum value followed by their decrease. The most important difference between a portable air conditioner and a nonportable system is the increase in cooling capacity with an increase in room temperature in full charge condition.

Heat and moisture transfer from skin to environment through fabrics: A mathematical model

2007 ◽  
Vol 50 (25-26) ◽  
pp. 5292-5304 ◽  
Author(s):  
Kyunghoon Min ◽  
Yangsoo Son ◽  
Chongyoup Kim ◽  
Yejin Lee ◽  
Kyunghi Hong
Keyword(s):  
Mathematical Model ◽  
Moisture Transfer ◽  
Heat And Moisture Transfer ◽  
Heat And Moisture
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