Development of heat recovery solution for heavy duty truck cabs to improve energy efficiency

The recent climate actions to reduce greenhouse gas (GHG) emissions have set the stage for decarbonizing the transportation sector through electrification, which has led to a surge in the deployment of battery electric Trucks (BET). While tail-pipe emissions are reduced drastically, certain aspects of BET prevent its widespread deployment, prominent of which is the range anxiety. BET range is heavily impacted in cold weather as energy from traction batteries is also used to warm the battery pack and cabin. The thesis mainly focuses on the cabin exhaust air ventilation, which accounts 7-42% of the heat losses. In this study, three heat recovery techniques were investigated to harness the waste heat from evacuating cabin air to reduce the heating energy consumption in a BET. One proposed technique employed an air-to-air heat recovery system (AAHRS). Baseline experiments were conducted on a Scania R20H test truck to analyse the performance of the installed Heat Ventilation and Air Conditioning (HVAC) system, which aided the design and prototyping of the AAHRS system. Validation experiments evaluated the energy savings from the prototype in a climate chamber under different ambient temperatures and HVAC fan speed settings. The study found a 20-53% reduction in heating load with the implementation of AAHRS. In contrast, the electrical power consumption increased 1.7-3.3 times higher than the baseline cases because of the additional power-consuming components and the changed system resistances. Overall, 19-47% energy saving was observed from integrating the AAHRS prototype with the existing HVAC system. Two other presented techniques operate on air-to-liquid heat recovery systems (ALHRS), which were coupled separately to a heat pump-assisted integrated thermal management system (ITMS). The two schemes were evaluated via vapour compression system performance analysis to see the potential to increase the coefficient of performance (COP), which is beneficial in terms of available heat that can be dissipated into the battery cold plates and cab heater core. To assess the energy-saving potential of proposed ALHRS solutions, a simulation model of an adopted baseline ITMS concept was developed using Engineering Equation Solver (EES) software. It was then validated against internal bench test results for a mock-up ITMS model. The results of the initial validation test indicated an absolute error between the simulation outputs and bench test results of 8-14% for condensation heat, while it was below 7% for all the other relevant performance parameters

UMSL Bulletin 2015-2016

https://irl.umsl.edu/bulletin/1000/thumbnail.jp

Full Proceedings, 2018

Full conference proceedings for the 2018 International Building Physics Association Conference hosted at Syracuse University

Near-entropy hotlink assignments

SCOPUS: cp.kinfo:eu-repo/semantics/publishe

Near-entropy hotlink assignments

Consider a rooted tree T of arbitrary maximum degree d representing a collection of n web pages connected via a set of links, all reachable from a source home page represented by the root of T. Each web page i carries a probability p i representative of the frequency with which it is visited. By adding hotlinks-shortcuts from a node to one of its descendents-we wish to minimize the expected number of steps l needed to visit pages from the home page, expressed as a function of the entropy H(p) of the access probabilities p. This paper introduces several new strategies for effectively assigning hotlinks in a tree. For assigning exactly one hotlink per node, our method guarantees an upper bound on l of 1.141H(p)+1 if d>2 and 1.08H(p)+2/3 if d=2. We also present the first efficient general methods for assigning at most k hotlinks per node in trees of arbitrary maximum degree, achieving bounds on l of at most {2H(p)}/{\log(k+1)}+1 and {H(p)}/{\log(k+d)-\log d}+1, respectively. All our methods are strong, i.e. they provide the same guarantees on all subtrees after the assignment. We also present an algorithm implementing these methods in O(nlog∈n) time, an improvement over the previous O(n 2) time algorithms. Finally we prove a Ω(nlog∈n) lower bound on the running time of any strong method that guarantee an average access time strictly better than 2H(p). © 2008 Springer Science+Business Media, LLC.SCOPUS: ar.jinfo:eu-repo/semantics/publishe