scholarly journals Design procedure for dual air handling unit of air-conditioning system

2018 ◽  
Vol 225 ◽  
pp. 04016 ◽  
Author(s):  
Azizuddin Abd Aziz ◽  
Daisuke Sumiyoshi ◽  
Yasunori Akashi
Keyword(s):  
Air Temperature ◽  
Air Conditioning ◽  
Load Capacity ◽  
Design Procedure ◽  
High Energy ◽  
Air Conditioning System ◽  
Typical Application ◽  
Air Handling Unit ◽  
High Humidity Environment ◽  
Psychrometric Chart

The use of conventional air-conditioning system in tropical climate is ineffective to reduce the humidity. In a typical application, the indoor temperature has to be overcooled to decrease the humidity which has an inherent effect of high energy consumption. The introduction of dual air handling unit (AHU) is the answer to high humidity environment. Each AHU is tasked to control the parameter of temperature and humidity respectively according to the desired value. In this paper, the objective is to design the procedure of sizing the dual AHU so that the control system could run efficiently. Basically, eight (8) steps are necessary to size the dual AHU system and the procedure requires sequential manner. Namely, the design process are indoor design condition, fresh air flow, outdoor design condition, room cooling load, capacity of both AHUs, supply air temperature of second AHU, supply air temperature of first AHU and the enthalpy of both AHUs. The design procedure also requires a psychrometric chart to indicate the air thermal condition throughout the cycle of the air-conditioning system. In conclusion, the proposed design procedure is simple yet effective for the application of dual AHU system to handle the excessive latent heat environment.

Comparing Cooling Energy between Existing Air-Conditioning System and Proposed Design System

2014 ◽  
Vol 699 ◽  
pp. 834-839
Author(s):  
M.M. Syafiq Syazwan ◽  
M.Z.M. Yusof ◽  
C.K. Chang ◽  
M.D. Amir Abdullah
Keyword(s):  
Air Conditioning ◽  
Cooling Capacity ◽  
Design System ◽  
Air Conditioning System ◽  
Air Handling Unit ◽  
Standard Operation ◽  
Air Ventilation ◽  
The Difference ◽  
Heat Loads ◽  
Psychrometric Chart

Air-conditioning (AC) system is typically used to remove the sensible and latent heat loads in buildings. It provides cool and dehumidified air to meet the occupants comfort and good indoor air quality (IAQ). Improper design and analysis of AC process resulted in high cooling energy and unsatisfied indoor humidity level in tropical climate. The objective of this study is to identify the cooling energy in hotel restaurant by comparing the design with proper fresh air ventilation design. The hotel restaurant was designed with primary air unit (PAU) and air handling unit (AHU) as to remove sensible and latent loads. The performance of the AC system has been monitored and analysed using psychrometric chart. For the AC air side system, 296.2 kW of cooling energy was used in standard operation. An alternative design was proposed for the said hotel restaurant employing only one AHU, with a cooling capacity of 165.9 kW which was 43 % lower than the existing system. The difference in temperature, humidity ratio and air flow rate influenced the cooling energy for AC system.

Theoretical analysis of heat and mass transfer processes in an evaporative cooling system with zeolite desiccant powered by solar energy

2018 ◽  
Author(s):  
◽  
Amged Al Ezzi
Keyword(s):  
Water Vapor ◽  
Flat Plate ◽  
Air Temperature ◽  
Air Conditioning ◽  
Cooling System ◽  
Evaporative Cooling ◽  
Air Conditioning System ◽  
Coating Method ◽  
Evaporative Cooler ◽  
Desiccant Material

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Concerns about energy sources depletion and environmental pollution issues have been raised and is a top priority of the global community. Refrigeration machines have been received the major of attention because of their energy consumption and pollution. Different from traditional cooling strategies, desiccant cooling technology (DCT) has been emergent as a promising alternative giving the fact that the economic-ecological air conditioning system is not restricted to hot and dry climates only. In the current experimental study, an advancement solar assisted desiccant cooling system (SADCS) is presented. The advantage is to use only a fraction of the energy of typical compressor-based cooling systems. The advancements have taken place into the dehumidification, evaporator, and regeneration sections. The role of appropriate choosing of the desiccant material type on the adsorption process has been presented, and a Faujasite (FAU) 13X zeolite is utilized in the dehumidification stage. A novel monolayer coating method has conducted. The new coating method has insured no external water vapor condensation ruins the desiccant material during relative humidity working range (20-97) %. Moreover, the new coating method allows to increase the performance of the adsorption and desorption processes, respectively. By giving the coming air stream the ability to pass through and surround the zeolite beads, accessibility to adsorb and desorb water vapor molecules is easier as more rooms are available. That clearly has been stated as 6450 g of zeolite holds 684 g of water in full saturation status within 37 minutes and regenerates by less than 120 [degree]C air temperature within 66 minutes. In the evaporative cooling section, an effective small compact evaporative cooler (CEC) system dealing only with product flow is introduced. The new CEC is utilized direct and indirect evaporation of water mechanisms combined in cross channels to cool air. Dropping air temperature by (5-7) [degree]C has recorded without desiccant stage. Supplying the required regeneration energy from a green energy source was essential in this study. For this purpose, an innovative flat plate double-mesh air solar collector has designed and carried out. In the new collector, a double copper mesh frames were fixing within a double Plexiglas covers flat plate collector. Experimental results show a good consistent with the mathematical model. With an average 0.71 solar fraction and 80 [degree]C exit air temperature, the collector presents 0.73 as thermal efficiency. As the improvements of the desiccant air-conditioning system turns out globally recognized by the progress in different research outcomes, designs, setting up and evaluation methods, it is expected that the system will be one of the most important alternative systems for the maintenance of human's environment comfort and air quality when considering the reduced dependence on conventional energy usage. Present work and results provide a reference data sets related to real adsorption dehumidification process and show that the advancement SADCS has a great potential in the future of the evaporative cooler systems.

scholarly journals Climate Compensation and Indoor Temperature Optimal Measuring Point Energy Saving Control in VAV Air-Conditioning System

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4398 ◽  
Author(s):  
Xiuying Yan ◽  
Cong Liu ◽  
Meili Li ◽  
Ating Hou ◽  
Kaixing Fan ◽  
...  
Keyword(s):  
Energy Saving ◽  
Air Temperature ◽  
Control Strategy ◽  
Air Conditioning ◽  
Compensation Scheme ◽  
Indoor Temperature ◽  
Air Conditioning System ◽  
Measuring Point ◽  
Temperature Measuring ◽  
Environment Control

Temperature measuring point is the key to room environment control. Temperature measuring points and climate changes are directly related to the room control effect. It is of great theoretical and practical significance to study the temperature measuring points and control strategy based on climate compensation. In this study, first, the climate compensation concept in a heating system was introduced into a variable air volume (VAV) air-conditioning system. The heating load was modeled as a function of supply air temperature by analyzing the heat exchange. Based on each control link of subsystems, a climate compensation scheme is proposed to determine the optimal set-point of the supply air temperature. At the same time, a layout of multiple temperature measuring points of an air-conditioned room was studied. Furthermore, the optimal indoor temperature measuring point was determined using an adaptive weighted fusion method. Finally, simulation results show that the proposed method has better control effects on indoor temperature adjustment compared with the traditional method. The optimal supply air temperature in summer and winter was determined according to the proposed climate compensation scheme, and the supply air temperature was controlled using an improved single-neuron adaptive control strategy. Experimental results show that the maximum energy saving can reach up to 35.5% in winter and 6.1% in summer.

Numerical simulation and mock-up experimental measurement of the air conditioning system for the 3 GeV Taiwan Photon Source electron storage ring

2010 ◽  
Vol 1 (MEDSI-6) ◽  
Author(s):  
J. C. Chang ◽  
Z. D. Tsai ◽  
C. Y. Liu ◽  
Y. C. Chung ◽  
J. R. Chen
Keyword(s):  
Numerical Simulation ◽  
Flow Pattern ◽  
Air Temperature ◽  
Storage Ring ◽  
Air Conditioning ◽  
Air Conditioning System ◽  
Utility System ◽  
The One ◽  
Radiation Research ◽  
Photon Source

National Synchrotron Radiation Research Center, Taiwan, is currently constructing the civil buildings and utility system of the Taiwan Photon Source. The air conditioning (AC) system of the storage ring tunnel was designed based on those of existing Taiwan Light Source and some international advanced accelerators. To predict the air temperature variation and flow pattern in tunnel more precisely, we applied 3D computational fluid dynamics scheme and built up a one-cell mock-up equipped with AC system. In the 3D numerical model, effects of magnets of the booster and the storage ring, girders, cable trays, front ends and the supplied air wind duct are all taken into account. The temperature variations and flow pattern were shown through the numerical simulation. Measured air temperature data in the one-cell mock-up were also collected.

Experimental Verification of a Universal Accumulator Heat Exchanger Design Procedure Used to Achieve Liquid Overfeeding Effects in Small Air Conditioning Systems

1999 ◽  
Author(s):  
Craig W. Wood ◽  
Josua P. Meyer
Keyword(s):  
Heat Exchanger ◽  
Experimental Verification ◽  
Air Conditioning ◽  
Pressure Ratio ◽  
Design Procedure ◽  
Cooling Capacity ◽  
Coefficient Of Performance ◽  
Direct Expansion ◽  
Air Conditioning System ◽  
Heat Exchanger Design

Abstract This study involves the experimental verification of a universal heat exchanger accumulator design procedure. A heat exchange accumulator was manufactured according to a mathematical model developed by the authors and installed into a small air conditioning system. Experimental results show that the addition of the heat exchanger accumulator results in a liquid overfeeding operation that replaces the previously utilized direct expansion operation. It provides an improved air conditioning system that has a 7.5% increase in coefficient of performance and a 4.4% increase in refrigerant mass flow rate. A pressure ratio reduction has a positive effect on the compressor performance and life span. Liquid overfeeding increases the cooling capacity of the system by 6.5%. When compared to direct expansion systems, this basic heat exchanger accumulator provides a reduction in cycling losses and power consumption, an increase in suction pressure and an improvement in isentropic compressor efficiency.

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