Numerical Study and Optimization of a Combined Thermoelectric Assisted Indirect Evaporative Cooling System

This paper numerically investigates the performance of a novel combined cross-regenerative cross flow(C-RC)thermoelectric assisted indirect evaporative cooling(TIEC)system.This C-RC TIEC system combines the indirect evaporative cooling and thermoelectric cooling technologies.A heat and mass transfer model is developed to perform the performance analysis and optimization of this novel system.Performance comparison between the novel C-RC TIEC system and a regenerative cross flow TIEC system is conducted under various operating conditions.It is found that the novel system provides better performance with higher coefficient of performance(C O P)and higher dew point effectiveness than the regenerative cross flow TIEC system,especially under smaller working current and smaller number of thermoelectric cooling modules.The performance optimization of the novel system is also made by investigating the influences of primary air parameters,three different mass flow rate ratios,as well as the length ratio of the left wet channel to the whole wet channel.The results show that there exist optimal mass flow rate ratios and wet channel length ratio resulting in the maximum C O P.

Heat and mass transfer model optimization and annual energy efficiency analysis for energy recovery indirect evaporative cooling

Indirect evaporative cooling(IEC)is a kind of high efficiency,energy-saving and environmental protection cooling technology,which has been widely used in data centers and other fields in recent years.In this paper,the optimized two-dimensional non-condensation state model of indirect evaporative cooling was proposed.Meanwhile the computer program was updated to solve the developed mathematical model under variable fresh air conditions.The optimized model was verified by the experimental data,and the maximum deviation was only 4.6%.Based on the modified model and the annual hourly meteorological parameters in Tianjin,China,it was analyzed the optimal heat transfer area of IEC used as fresh air pre-cooling unit under various air volumes to provide references for system design and equipment selection.Finally,taking an IEC-primary return air conditioning system of a gymnasium as an example,the hourly energy-saving effect of whole year was simulated by the developed IEC model.The simulation results showed that IEC could control the fresh air temperature below 27℃ and the moisture content below 18 g/kg throughout the year,and undertook 102.6% of the total fresh air cooling load.The findings are useful in future system optimization and design of IEC equipment.

Performance analysis and optimization of free cooling strategies for a liquid-cooled data center

The increasing power density of IT electronics and the enormous energy consumption of data centers lead to the urgent demand for efficient cooling technology.Due to its efficiency and safety,liquid-cooled heat sink technology may gradually replace air-cooled technology over time.With the ambient or higher water supply temperature,the liquid-cooled technology shortens the operating time of the chiller and improves its coefficient of performance,while the pump power consumption may increase for satisfying the constant cooling capacity.Therefore,it is significant to study the optimal water supply temperature to achieve energy-efficient operation of data centers.A virtual 30.1 kW data center is considered as the case,the liquid-cooled system is constructed with a combination of innovative manifold microchannel heat sink with oblique fins and indirect evaporative cooling technology to minimize energy consumption.A hybrid thermal management model integrating the heat dissipation model and the power consumption model is established by TRNSYS and FLUENT software.To the highest chip-safe operating temperature premise,the energy performance is analyzed under various water supply temperatures in Guangzhou.The result shows that only 21.5-hour mechanical cooling is needed with the 30℃server inlet temperature throughout the year.And the minimized power consumption occurs with the constant 29℃server inlet temperature.Moreover,the temperature adaptive control strategy(TACS)is adopted to test the cooling system power consumption under different regulation frequencies,and the by-week TACS can achieve another 11.5%energy saving than the minimum power consumption of the constant temperature control strategy.

LINKING CONSTRUCTIVE AND ENERGY INNOVATIONS FOR A NET ZERO-ENERGY BUILDING

This article explains the design,construction and energy strategies of LINQ,a net-zero energy building that was successfully entered into the Solar Decathlon Middle East 2018 held in Dubai.Students of engineering,building physics,architecture and urban planning designed,built and operated LINQ.It is mainly powered by solar energy and made of bio-materials.Some of LINQ’s innovations are the ventilated façade with customizable bio-based tiles,the indirect evaporative water cooling system,and the light building integrated photovoltaic-thermal system.LINQ sent more energy to the grid than it drew throughout the competition.However,energy production could have been improved according to simulations and technical specifications.LINQ is a good example of current and future building expectations-combining multiple criteria,strategies,and solutions-to contribute to environmental,social and economic sustainability.