How NEWBASE HV-Rooftop Heat Pump HVAC + BTMS Cuts TCO and Boosts Range

As global transit authorities accelerate the transition to zero-emission fleets, one engineering challenge has moved to the forefront: efficient, integrated thermal management for new energy buses (NEBs). Air conditioning alone can account for 25–35% of auxiliary energy consumption in a battery electric bus (BEB), while improper battery temperature control remains a leading cause of premature pack degradation. Legacy approaches—installing a standalone roof A/C plus a separate chassis-mounted battery chiller—introduce redundant hardware, extra refrigerant lines, higher weight, and increased leakage risk.

Zhengzhou Newbase Auto Electronics Co., Ltd. (NEWBASE), a China-based specialist in commercial vehicle thermal management and new-energy electronic control, addresses this with its NBEAC Series Full DC Inverter Heat Pump Air Conditioning Systems, including the "-T" integrated variants​ that combine passenger compartment HVAC with liquid-cooled Battery Thermal Management System (BTMS) in a single roof-mounted unit.

In modern 6–12 m electric, hybrid, or fuel-cell buses equipped with liquid-cooled battery packs, thermal loads come from two primary sources:

• Cabin load:​ Sensible + latent heat removal in summer; heating demand in winter

• Battery load:​ Active cooling during fast charge / peak discharge; heating or insulation in low ambient

When these functions are decoupled, each subsystem requires its own compressor, condenser, expansion device, and controller. Integrated thermal management consolidates these functions around a shared vapor-compression loop, intelligently distributing refrigerant between the cabin evaporator and the battery-side plate heat exchanger.

Industry studies on EV thermal integration indicate that centralized thermal management can:

• Reduce system mass by 15–25%

• Lower first-cost component count and installation labor

• Improve overall system COP through coordinated capacity modulation

• Enable simultaneous cabin heating and battery cooling—critical in extreme climates

The NEWBASE NBEAC-21-T / 24-T / 30-T / 34-T models are engineered for exactly this purpose. Core characteristics drawn from product specifications:

A single (or dual, model-dependent) DC inverter electric compressor—typically HIGHLY (海立) brand, optionally Denso or Copeland—driven by NEWBASE's proprietary controller with CAN J1939 interface, modulates capacity from minimum to full load using PWM stepless control. This avoids the cycling losses of fixed-speed systems and maintains tighter temperature control.

A key differentiator cited in NEWBASE's technical documentation is the pioneering use of multi-channel EEVs and P+T pressure-temperature sensors. The onboard PID algorithm continuously balances refrigerant flow between:

• Cabin evaporator circuit (passenger cooling/heating via reverse-cycle heat pump with four-way reversing valve)

• Battery coolant circuit (liquid-cooled via brazed plate heat exchanger)

This solves the common integrated-unit problem of "starvation" on one side when the other side calls for maximum cooling.

In cold-weather scenarios, the heat pump provides cabin heating while the same system actively cools the battery pack during charging or after hard acceleration, helping keep Li-ion cells in their optimal 20–35°C window and extending calendar life.

According to NEWBASE product data:

• System cost reduced by ~30% vs. separate A/C + battery chiller

• Overall weight reduced by ~20% (typical saving: 30–50 kg depending on model)

• Fewer through-roof penetrations and refrigerant joints → lower leak risk & easier service

For fleets already using a separate battery cooling solution, NEWBASE also supplies the NBEAC-21 / 24 / 30 / 34​ pure cabin heat pump A/C units:

Refrigerant: R407C / R410A. Operating voltage: 420–750 V DC. All fans are brushless EC type (FENSTARS / EBM / SPAL).

Beyond integration, NEWBASE emphasizes several efficiency-oriented features relevant to BEB range extension:

• Low-Temp Enthalpy Injection (EVI):​ On applicable variants, addresses heat pump capacity drop below −10°C and improves heating COP.

• Fuzzy Logic Energy-Saving Control:​ The controller unloads or down-speeds major consumers based on real-time ΔT (inside-outside), maintaining setpoint with minimal kWh draw.

• CAE/CFD-Optimized Duct & Coil Design:​ Evaporator and condenser cores use inner-grooved copper tubes with aluminum fins (Yuxin-supplied); evaporator/condenser fan blade geometry is optimized to reduce audible noise and vibration.

• Cabin Temp-Humidity Curve Control:​ Developed referencing European comfort models, the system avoids over-drying or over-cooling.

Together, these measures contribute to measurable reductions in daily HVAC energy consumption—particularly important in stop-and-go urban duty cycles.

Transit-grade durability is addressed through:

• IP67-rated electric compressor, EEV, and sealed connectors​ — resistant to dust, water spray, and temporary immersion

• EMC compliance to national Class I / UN ECE R10 level, protecting sensitive vehicle electronics

• High-Voltage PDU with pre-charge circuit & fuse protection, plus optional integrated DC-DC (2 kW / 3 kW) converting HV to 24 V auxiliary power

For modern fleet management, NEWBASE offers optional cloud-connected telematics:

• Real-time monitoring of superheat, subcool, pressures, voltages, and fault codes

• Historical data logging accessible via PC software or mobile app

• Supports condition-based maintenance to reduce roadside failures

Choosing an integrated thermal management platform such as the NEWBASE NBEAC-T series delivers benefits across the vehicle lifecycle:

✅ Extended Range​ — Less HVAC energy draw + lighter weight → more km per charge

✅ Battery Life Protection​ — Precise thermal control during charge/discharge cycles

✅ Lower TCO​ — Fewer parts, simpler assembly, reduced service interventions

✅ Regulatory Alignment​ — Meets EMC, IP, and environmental refrigerant standards

✅ Scalable Architecture​ — Same control platform scales from 6 m midibuses to 12 m articulated units

As electric bus platforms migrate toward 800 V architectures and higher energy-density battery packs, integrated thermal management will shift from "value-add" to mandatory best practice. NEWBASE's rooftop-integrated heat pump + BTMS product family represents a production-validated step in that direction, supporting OEM customization for regional climate and duty-cycle requirements.

For technical datasheets, 3D models, or application engineering support tailored to your bus platform, please contact the NEWBASE International Sales Department.